In breast tumor-derived cells with different phenotypes, we demonstrated that the expression of CD133 is strongly correlated to the levels of the beta2 isoform of the phosphoinositide-dependent phospholipase C (PLC-β2) [17, 18], ectopically expressed in the large majority of primary invasive mammary tumors of all histological subtypes [19]. The gene discussed is PLCB2; the disease is breast neoplasm.