PIK3CB and cancer: There are three class IA p110 isoforms (α, β, δ) expressed by the genes phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), PIK3CB and PIK3CD, respectively, of which PIK3CA is the most frequently mutated in multiple cancer types, including EOC[37,39].