CASP3 and neoplasm: Moreover, immunohistochemical staining showed that the Ki67 expression was lower, and the caspase 3 expression was higher in 131I-Var3-pHLIP-treated mice than in the other three groups (Figure 6), suggesting that 131I-Var3-pHLIP reduced tumor growth and increased apoptosis in MDA-MB-231 xenografts.