Treated with the PI3K siRNA 1178, 619 and 856, the expression of PI3K, p-Akt (ser473) and p75NTR in ESCC cells were all significantly (P<0.01-0.001) decreased in siRNA group, compared to control siRNA group, (Figure 5A, 5C and Figure 6A, 6C), but no significant alternations were observed in total Akt expressions (Figure 5A, 5C and Figure 6A, 6C). The gene discussed is AKT1; the disease is esophageal squamous cell carcinoma.