PIK3CG and cancer: Three classes of PI3Ks, class I, class II, and class III, have been identified, each of which has specific substrates and distinct effectors in addition to the common substrate Akt (Table 1).3 To date, class I, class II and class III PI3Ks have been widely mentioned in former studies.7,8 Further understanding the PI3K isoforms will help to fully elucidate the biological processes in various types of cancer cells.