CDK4 and neoplasm: Overactivated pro-survival and pro-proliferative signaling pathways, seen in majority of the cancers, leads to stimulation of specific p27KIP1 phosphorylation which in turn results in cytoplasmic localization, emergence of tumor-promoting functions of p27KIP1 such as enhancing of Cyclin D/CDK4/6 complex assembly or EMT and invasiveness boosting (Fig. 3A).