ABCG2 and neoplasm: Activation of ABC transmembrane transporter member-2 (ABCG2)Cooperation with LGR5 and LGR6 stemness markers for activation of the pathway in OCSCsRegulation of EMT through increase of the SNAIL/E-cadherin ratio and enhancement of OCSC motility and chemoresistancePromotion of pro-inflammatory and tumor-supporting phenotype of CAFs