To investigate the requirement of E2s for APC/C activity in mitosis, we generated UBE2C- and UBE2S-knockout (ΔUBE2C and ΔUBE2S) HCT116 (a human colorectal carcinoma cell line) cells using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology (Cong et al., 2013, Mali et al., 2013; Figure 1A). The gene discussed is APC; the disease is colorectal carcinoma.