PIK3CA and cancer: Motivated by the need to understand the role of PI3K signalling in a human developmental context, we previously generated an allelic series of human induced pluripotent stem cells (iPSCs) with heterozygous or homozygous expression of the activating mutation PIK3CAH1047R, the most commonly observed PIK3CA mutation in both cancer and PROS (Madsen et al., 2019).