USP21 and malignant colon neoplasm: Using CRISPR-Cas9 gene editing, we generated three distinct USP21-KO colon cancer cell lines: USP21-KO HCT-15, USP21-KO HT-29, and USP21-KO SW480 (Fig. 1F, three gRNAs for USP21 and Cas-9 vector; Fig. 1G, USP21-KO HCT-15; Fig. 1H, USP21-KO HT-29; Fig. 1I, USP21-KO SW480).