In contrast, CDKN1C knockdown in chemosensitive cells led to markedly increased IC50 values (Figures 4C, S2C, right panels) and reduced apoptosis (Figure 4D2) after exposure to cytotoxic drugs, indicating that CDKN1C negatively regulates SCLC chemoresistance. Here, CDKN1C is linked to small cell lung carcinoma.