Effect of WISP-1 knockdown on cell apoptosis in human oral squamous cell carcinoma cells. The proportion of apoptotic cells observed for WISP-1 knocked down cells was greater compared with the negative control cells (8.8+3.4 vs. 12.6+10.5%). C, negative control siRNA-transfected cells; W, WISP-1-specific siRNA-transfected cells; WISP-1, WNT1-inducible-signaling pathway protein-1; siRNA, small interfering RNA; 7-AAD, 7-amino-actino mycin D.