CASP3 and neoplasm: Immunohistochemical analysis of PDX xenograft tumor tissues from HCPT- or vehicle-treated groups also showed reduced expression of Ki-67 and TOP I and increased expression of cleaved caspase-3 and H2A.XS139 in HCPT-treated tumors (Figure 5G,H, Figure S4), further supporting the anti-proliferative and apoptosis inducing effect of HCPT on ESCC.