p110α (PI3K catalytic subunit) overexpression was present in 19% of the tumours (24/125), and PIK3CA somatic missense mutations were identified in 17% (24/142): in exon 20 (nucleotide A3140G, amino acid H1047R) in 15% of the tumours (21/142), whereas mutations in the helical domain of exon 9 (nucleotide G1635C, amino acid E545D) were detected in only 6% (3/50). The gene discussed is PIK3CA; the disease is neoplasm.