Morphology and viability of MCF7 and MCF7-CR cells in the presence of cisplatin: (A) Surviving MCF7 cells following cisplatin treatment showed an enlarged morphology (right panel), compared to the untreated cells (left panel). They were also found to attach stronger to flask surfaces (right panel). Magnification: 200×. (B) MCF7 cells that survived the seven-cyclic exposure to cisplatin were maintained for another 30 days in drug-free media prior to the infection experiment. The morphology of these MCF7-CR cells reverted back to the morphology of the parental MCF7. Magnification: 100×. (C) An increased IC50 was observed in the MCF7-CR compared to the MCF7 cells.