SNAI1 and neoplasm: Other double-negative feedback loops operate between miRNAs and EMT-TFs were reported in multiple processes of tumor epithelial–mesenchymal transition, including miR-34/miR-203 and SNAIL1, miR-1/miR-200 and SNAIL2, miR-33a-5p and ZEB1, miR-145 and ZEB2, miR-200 and Foxf2, miR-30a and SOX4, or miR-15a/16-1 and AP4 [133, 134, 137, 139–143].