CCND2 and breast cancer: miR‐206 functions as a novel cell cycle regulator and tumor suppressor through regulation of various genes, such as the gap junction protein connexin 43 in breast cancer 39, 40, the apoptosis‐suppressing gene BCL‐2 in glioblastoma and HCC 22, 41, tRNA threonyl carbamoyl transferase subunit YRDC in bladder cancer 42, cell cycle activators cyclinD2 in laryngeal squamous 43 and gastric cancer 44, and the vascular endothelial growth factor VEGF in laryngeal cancer 45.