CD44 and cancer: In comparison to MDA-MB-231 cells, radioresistant MDA-MB-231/IR cells showed higher expression of the CSC-associated marker proteins, and PEITC exposure to these cells suppressed cancer cell stemness through the down-regulation of CSC markers such as CD44, oct3/4, and Slug, and the down-regulation of metadherin protein at the post-transcriptional level [103].