Bilirubin (BIL), formed in erythroid cells, exits the cell to be transported to the liver for conjugation and ultimately, excretion. BIL possibly leaves the cell by simple diffusion as it is highly lipophilic (Kamisako et al. 2000). However, the multidrug resistance-associated protein 1 (ABCC1 aka MRP1) is known to mediate the ATP-dependent export of organic anions and drugs from cells. Unconjugated bilirubin (BIL) may also be exported from cells by ABCC1 (Rigato et al. 2004).