KRT18 and breast cancer: Regarding the CK expression in BC-PDMs, we observed similar cellular profiles as described previously by Abd El-Rehim, D.M. et al. [44], i.e. the differentiated glandular phenotype (CK18+), the stem cell phenotype (CK5/6+) and an intermediate glandular phenotype (CK5/6+, CK18+) [48].