NRAS and melanoma: Retraction: 'Effects of miR-145-5p through NRAS on the cell proliferation, apoptosis, migration, and invasion in melanoma by inhibiting MAPK and PI3K/AKT pathways,' Sha Liu, Guozhen Gao, Dexiong Yan, Xiangjun Chen, Xingwei Yao, Shuzhong Guo, Guirong Li, Yu Zhao, Cancer Medicine.