Kees wanted to become an investigator, even when he was little. "My father was an electronic engineer. He showed me that nothing was too difficult; you just had to try. And that's what I did. I took all kinds of devices apart to see how they worked. The trick was to put them back together again after inspection. And I usually managed."
He even decided to build an electronic organ together with a friend. "My friend’s father also worked in electronics, which is how we managed to acquire the materials. We tried to be creative in our pursuits – by painting and playing guitar, for example. Yes, I think it’s fair to consider us nerds, but I'll take that as a compliment."
After high school, he "naturally" went on to study at university. "My parents never had the opportunity to study. I decided to enroll in biology. Birds, plants, insects, everything was wonderfully interesting to me. Parasitic wasps were my specialty. I ended up graduating as an ecologist and archaeologist. We organized nature excursions throughout the country, by train and bike. It was an amazing time."
Shortly after, he was offered what he initially saw as the ideal internship, together with a friend. "Diving in Curaçao for a year to find out why there were so few lobsters on the island. Complete freedom, diving to our heart's content! But after one year we had collected so little data that we couldn’t draw a single conclusion. That was way too slow for me."
Kees returned to the Netherlands, disillusioned. He went on to study electrophysiology in Leiden. "Cells communicate with each other, and one of their methods is through electric signals. With the right equipment, we can measure these signals. If your amplifier is good and fast enough, you can decipher how a cell “thinks”. This work was so much more dynamic and matched my interest in electronics. This is where my love for biophysics originated."
After graduating in 1987, his eye fell on a vacancy in Amsterdam, in Wouter Moolenaar's lab. "This is where I wanted to do my PhD. I would show up at the lab at 8:15 every morning, the first to arrive. Hidde Ploegh, our section leader, would often sit with me for half an hour, first thing in the morning, just to have a chat about all kinds of stuff. I learned a lot from him and try to do the same now that I'm a group leader myself: make time to talk with my PhD students."
As a PhD student, Kees preferred to take his time with his measurements. "Wouter asked me to examine a certain substance that could increase the amount of calcium in a cell. It turned out that a certain impurity in the substance was responsible for the increase – a fatty substance, lysophosphatidic acid, or LPA in short."
After at least two hundred measurements, Kees was certain that his findings were correct and wrote an article. "When I showed Wouter, he was skeptical, to say the least. I must have made a miscalculation. There was no other explanation. Nothing in the existing literature seemed to confirm what I had found. But it turned out to be the beginning of a new field of study: fatty substances like LPA can also transfer signals between cells. Wouter spent much of his career building on that."
His time as a PhD student led to thirteen articles. "I wrote them on my typewriter; we didn’t have word processors yet at the time. We would use black adhesive letters to create figures. Even simple observations could lead to publications. I am very precise in my content. A single control test can completely undermine your insights. There's no such thing as a partial understanding; you can't publish your findings when you're at that point."
After his PhD, he left for San Diego in 1994. "I joined the lab of future Nobel laureate Roger Tsien, where I worked with fruit flies and witnessed the birth of FRET, Fluorescence Resonance Energy Transfer. I have learned a lot from Roger, including that it can be better to follow your intuition in science, instead of making everything a product of logical reasoning."
Kees returned to Amsterdam in 1997, this time as a group leader in the Biophysics of cell signaling. "Piet Borst, our scientific director at the time, asked me to focus on something else than LPA. In retrospect, it may have been stupid of me to accept, considering how much research is being conducted into LPA nowadays. But there was still plenty to investigate – like the mechanisms that provide the coding in the signals that cells send. You can measure those in living cells with an advanced microscope."
Research like that motivates him as much as ever, even after all those years. "I haven’t been at the lab as often, but that’s only because of COVID-19. It is very inspirational to work with young researchers. Students who want to pursue science. Or one of those enthusiastic AIOs full of intrinsic motivation. I recognize myself in them."