Abstract
In recent years, many groups have detected biomarkers of cellular senescence in a plethora of neoplastic lesions, in model systems, and humans. Indeed, we have come to realize that oncogene-induced senescence (OIS) acts as a potent barrier to oncogenic transformation, operating alongside cell death programs. We have begun to uncover some of its underlying principles, but many fundamental questions remain. In this perspective, some of the 'knowns' and 'unknowns' of OIS are discussed, with a focus on melanomagenesis.