Moreover, hypoxia can enhance the stemness of tumor cells by upregulating CSC markers such as CD133, CD44, SOX2, OCT3/4, and NANOG, thereby activating the EMT process and promoting the formation of VM (Pietras et al., 2014; Iida et al., 2012; Bhuria et al., 2019). This evidence concerns the gene CD44 and neoplasm.