To investigate the association between GRP94 expression and the metastatic potential of breast cancer, we conducted western blot analysis to assess endogenous GRP94 levels in a panel of breast cancer cell lines, including non-metastatic luminal cell lines (MCF7, T47D, and BT474) and metastatic triple-negative breast cancer (TNBC) cell lines (Hs578T, MDA-MB231 and MDA-MB157). This evidence concerns the gene HSP90B1 and breast cancer.