Effects of Beclin 1 expression on proliferation, apoptosis, autophagy and differentiation of HCT-15 and HCT-116 cells. Beclin 1 expression in HCT-15 and HCT-116 cells was determined following transfection with pcDNA3.1-Beclin 1 using (A) reverse transcription-quantitative polymerase chain reaction, (B) immunofluorescence and (C) western blotting. (D) The transfectants exhibited a decrease in viability in comparison with the control and mock. Beclin 1 overexpression may (E) improve the differentiation of HCT-15 and HCT-116 cells as identified by ALP activity and promote autophagy as determined by (F) electron microscopy (red arrow indicates the autophagosome) and (G) marked LC-3B staining. (H) Forced Beclin 1 expression induced the G2 arrest of HCT-15 cells, but the G1 arrest of HCT-116 cells. (I) Apoptosis was increased by Beclin 1 overexpression, as identified using an Annexin V assay. Results are representative of three independent experiments and are expressed as the mean ± standard deviation. *P<0.05 vs. mock and control groups. ALP, alkaline phosphatase; LC-3B, light chain 3B; Ctr, control; C1, clone 1; C2, clone 2.