PIK3CA and breast cancer: Inhibition of KDM6B with GSK-J4 has been demonstrated to sensitise luminal breast cancer cell lines, including those that harbour mutations in the PIK3CA gene, to apoptosis induced by phosphoinositide 3-kinase (PI3K) inhibitors, which have shown limited or suboptimal efficacy in late-phase clinical trials in luminal breast cancers with PIK3CA mutations [41].