MKI67 and head and neck squamous cell carcinoma: CSCs and CDDP-resistant HNSCC cells tumors grew slowly and showed higher tumorigenic potential by increasing: (i) tumorsphere-forming ability and CSC properties; (ii) Ki-67-positive cell numbers; (iii) tumor heterogeneity; and (iv) metastatic ability (only for CSCs) compared to parental cells.