PMAIP1 and esophageal squamous cell carcinoma: Our data showed that Noxa knockdown with siRNA significantly suppressed FCL-induced intrinsic apoptosis, as evidenced by (i) the attenuated percentage of Annexin V-positive cells (Figures 4D, E), and (ii) the reduction of the cleaved fragments of PARP (Figure 4F), demonstrating that FCL induced Noxa-dependent intrinsic apoptosis in ESCC cells.