CISH and ovarian cancer: The CIS-resistant (A2780CR1, A2780CR2), PAC-resistant (A2780PR1, A2780PR2), DOX-resistant (A2780DR1, A2780DR2) and TOP-resistant (A2780TR1, A2780TR2) variant sublines of the A2780 human ovarian cancer cell line were all established by the stepwise selection of A2780 cells cultured in growth media with increasing drug concentrations.