In the light of the experiments shown here where LY294002 causes ERα down regulation both in C4-HD and C4-HI tumors (Figure 6) but tumor regression, by apoptosis and differentiation, only in C4-HI tumors (Figure 1), we postulate that AKT regulates C4-HI tumor growth, at least in part, by keeping ERα levels. The gene discussed is ESR1; the disease is neoplasm.