To validate the functions of xIAP and cIAP1 in Fas-mediated apoptosis in human colon carcinoma cells, SW620 cells were transfected with xIAP- and cIAP1-specific siRNAs, respectively (Figure 8A), and analyzed the tumor cell sensitivity to FasL-induced apoptosis (Figure 8B). Here, FAS is linked to colon carcinoma.