A recent study reported that the reduced efflux efficiency of ABCB1 substrate Rh-123 and [3H] daunorubicin post-tariquidar (100 and 50 nM) pretreatment retained 80% and 50% Rh-123 after 2 h of efflux, which enhanced the sensitivity of MDR EMT6/AR1.0 murine mammary carcinoma cells to paclitaxel, Dox, vincristine, and etoposide [70]. Here, ABCB1 is linked to breast carcinoma.