ABCG2 and neoplasm: Given the importance of the growth factor IGF-I in the interactions of tumor cells with stromal cells in the microenvironment, in the present study, we investigated a possible involvement of this growth factor in the regulation of ABC gene expression (MDR1, MRP1, MRP2, MRP3, MRP5 and BCRP) and its impact on the resistance of OVCAR3 cells in the presence of Hospicells against carboplatin or taxol.