Subsequently, to investigate whether SMAD7 is essential in Tan IIA-mediated apoptosis in liver cancer cell lines, we performed IF analysis to test the level of the apoptosis marker cleaved caspase substrate and found that SMAD7 knockout can impair the apoptosis-inducing ability of Tan IIA in Bel-7404 cells (Figure 5C). Here, SMAD7 is linked to liver cancer.