CDK4 and neoplasm: In this study, we found that miR‐21 is intricately involved in apoptosis and cell cycle regulation through its modulation of several genes, including but not limited to AR, BCL2, BRCA2, CASP3, CASP9, CCNB1, CDC25A, CSK1, Cyclin‐Dependent Kinase 2 (CDK2), CDK4, EPCAM, ERBB2, MMP1, MSH3, PARP1, etc. EMT, a fundamental process during embryonic morphogenesis, becomes co‐opted by tumor cells to execute the multifaceted stages of tumorigenesis and metastasis.