CASP3 and neoplasm: Immunohistochemical staining of tumor tissues revealed that the combination of 5FU + RT synergistically suppressed the expression of proliferation marker Ki67 and anti-apoptotic protein Bcl-2 while promoting the expression of apoptotic marker Cleaved Caspase-3 and DNA damage marker γH2AX, consistent with TUNEL staining results (Fig. 6F, G).