HMMR and breast cancer: RHAMM full-length protein was confirmed to be expressed in Wildtype but not Rhamm−/− MMTV-PyMT tumors (Fig. 1C), and immunofluorescent analyses further show that RHAMM protein expression is heterogeneous in Wildtype primary tumors, similar to human breast cancers [37], and also occurs in host cells of the tumor microenvironment (Fig. 1D).