ABCG2 and cancer: The protein expression levels of epithelial-mesenchymal transition markers such as E-cadherin and N-cadherin, cancer stem cell markers such as vimentin and ALDH1 and ATP-binding cassette (ABC) transporters such as ABCB1 and ABCG2, which are known to be involved in mechanisms of resistance development to cytotoxic agents, were not changed (data not shown).