Other studies using functional assays such as sphere formation has also identified a number of markers in the putative CSCs in RCC cell lines, including EMT markers CXCR4, SDF-1, ZEBs, TWIST, N-cadherin, and Vimentin, as well as canonical stem cell markers such as OCT4, NANOG, KLF4, CD24, and CD44 (Studies 13 and 14 in Table 1) [90, 91]. This evidence concerns the gene CD44 and renal cell carcinoma.