PIK3CA and neoplasm: Conversely, activating mutations in the PIK3CA gene (PI3-kinase, p110 alpha subunit) were observed in four cases (22%) of liposarcoma (Figure 1) One tumor sample (Patient #203, female) harbored the E542K (1624G>A) mutation located with the helical domain of PIK3CA, and three cases (Patient #166, 1000, 1001, all male) carried the H1047R (3140A>G) mutation located with the PIK3CA kinase domain.