These are heterodimeric proteins with one catalytic subunit of which there are three isoforms, each of them related to a specific gene: p110α/PIK3CA, p110β/PIK3CB, p110δ/PIK3CD, plus a regulatory subunit associated with cancer development by increasing cell survival, cell proliferation and conferring apoptosis resistance [35]. The gene discussed is PIK3CB; the disease is cancer.