PROM1 and breast cancer: Liu et al. found that PROM1 was not expressed in the cells of normal breast tissue, but the expression rate increased with progression of lesions from usual hyperplasia, through atypical ductal hyperplasia, ductal carcinoma in situ, and invasive carcinoma, suggesting that PROM1 positive breast cancer cells were closely related to invasiveness and its expression may predict a poor prognosis [26].