PIK3CA and breast carcinoma: In this context, PIK3CA, the catalytic subunit of PI3K, is one of the most recurrently mutated genes in breast cancer [73] and cervical cancers [74], and PI3K inhibition has seen some success in pre-clinical and clinical trials, particularly as combination therapy with CDK4/6 [75], MEK [76] and PARP inhibitors [77].