CDKN1A and breast cancer: Therefore, by determining the role of miRNAs (hsa-mir-638, hsa-mir-665) and mRNAs (PTEN, TP53, SOX2, CDKN1A, MGMT, IGF2, CDK2, CCND2) involved in this network, it is suggested that hsa_circ_0020397 may have a major function in BC.