SLC25A21 and breast cancer: Adding to the discourse of how significant efflux transporters may contribute to reactivity and response to chemotherapy, a recent study demonstrated that the overexpression of the mitochondrial carrier SLC25A21, pertaining to the solute carrier superfamily 25, halted the growth, migration, and invasion of bladder cancer (BC) cells in vitro and suppressed the growth of the BC cells in an in vivo nude mouse model.