miR-21 is not only upregulated in cRCC but is also involved in cancer progression (proliferation, migration, invasion, epithelial mesenchymal transition) and the cancer stem cell phenotype by targeting tumor suppressor genes such as PTEN, PDCD4, TIMP3 or LATS1 [84,85,96,97,98,99,100,101,102,103,104]. Here, PDCD4 is linked to cancer.