PIK3CA and cancer: Interestingly, whereas transgenic overexpression of mutant Pik3ca has been found to be an effective inducer of cancer8, other models, in which mutated Pik3ca is expressed from its endogenous locus, demonstrate that mutant Pik3ca, on its own, is a weak oncogene (see for example ref. 9), with cancer arising only after long latency periods (>1 year; reviewed in ref. 10).