CD44 and neoplasm: circRGPD6 overexpression in vitro contributes to depletion of tumor-initiating properties and pluripotency capabilities of BCSCs as evident by reduced proportion of CD44+CD24− cells, suppressed expression of stem cell marker CD44, enhanced expression of DNA damage marker p-H2AX, differentiation markers-Muc1 and α-SMA, and vimentin and E-cadherin.