Interestingly, it was recently described that E-selectin plays an important role in facilitating entry of breast cancer cells to the BM, where they are then retained by CXCR4.38 We believe that E-selectin may play a similar role in MM enabling the homing of MM cells to the BM in cooperation with CXCR4, inducing chemoresistance via cell adhesion-mediated drug resistance. This evidence concerns the gene CXCR4 and breast cancer.