CCNB1 and breast cancer: To delve deeper into the involvement of KPNA2, FOXM1, CCNB1, and CCNB2 expressions in BC molecular subtypes, we conducted an analysis of these four genes’ expression levels and their association with OS and DSS in the TCGA dataset, stratified by ER, PR, and HER2 status using Kaplan–Meier plots.