These contradictory results could be due to the molecular heterogeneity of PCa, and a pointer toward the drivers of malignancy in the particular tumor cells, for example; whereas ABCB1 down-regulation would be advantageous for androgen-sensitive PCa, as an androgen-insensitive PCa would not be under selective pressure to down-regulate ABCB1. The gene discussed is ABCB1; the disease is neoplasm.