Our findings that BYL719 fails to fully reverse the increased NODAL and stemness gene expression in homozygous PIK3CAH1047R iPSCs suggests that inhibition of TGFβ signalling as a pro-differentiation therapy warrants investigation as a co-therapy with PI3K inhibitors in breast tumours with strong PI3K pathway activation. The gene discussed is TGFB1; the disease is breast neoplasm.