Abstract
Gene disruption and overexpression in mice can be combined with proviral tagging to investigate the biochemical pathways in which oncogenes act. The phenomenon of oncogene collaboration permits a focussed genetic approach analogous to the strategies employed in suppressor screens in invertebrates and yeast. We illustrate here its application to investigating the action of the pim kinases in tumorigenesis. However, it should be possible to utilize this strategy for dissecting a much wider range of biochemical pathways in mammalian systems.