PIK3CA and neoplasm: The thienopyrimidine PI3K inhibitor, GDC-0941, preferentially inhibits the α and δ p110 isoforms of PI3K over the β and γ isoforms in an ATP-competitive manner, has potent preclinical tumour growth inhibitory activity, and has recently entered phase I trials (Folkes et al, 2008; Maira et al, 2009; Raynaud et al, 2009).