Furthermore, USP21WT, but not USP21C221A mutation, significantly promoted tumor growth and upregulated Ki-67 protein levels in subcutaneous xenograft models (Fig. 2M–O, Fig. S5A) and increased the number of metastatic nodules in experimental mice models with lung metastasis (Fig. 2P, Q, Fig. S5B). Here, MKI67 is linked to neoplasm.