After repeated i.p. administration, tumor PCNA protein expression detected by IHC. (A) and apoptosis examined by TUNEL assay (B). Quantitative analysis data revealed 37% reduce in cell proliferation index in LPEI/siRNA-EGFR group compared with other two groups (C), and more than twofold increase in apoptosis index under LPEI /siRNA-EGFR treatment (D). All the results are shown as the mean±standard error of numbers obtained from 6 animals in each group. *P < 0.05.