In the presence of cetuximab, knocking out PD-L1 in CRC cell lines obviously decreased cell viability (Fig. S2B), inhibited proliferation (Fig. S2C), promoted apoptosis (Fig. S2D), and led to an increase of cleaved caspase-3 and a decrease of uncleaved PARP (Fig. S2E). The gene discussed is CASP3; the disease is colorectal carcinoma.