PIK3CA and neoplasm: Additionally, a greater understanding of the specific roles of the p110α and p110β isoforms in tumourigenesis has recently been established: it has been shown that p110α is critical for the growth of tumours driven by PIK3CA mutations as well as oncogenic receptor tyrosine kinases and RAS, whilst p110β is the principal isoform involved in mediating PTEN-deficient tumourigenesis [11-13].