ABCG2 and central nervous system cancer: In our studies, we chose to explore the ABCB1 substrate doxil, and Zhou et al. found that ibrutinib’s use in human-derived glioma rodent models demonstrated additive cytotoxicity with etoposide (ABCB1 and ABCC1 substrate), which suggests that ibrutinib may target more than just one ABC transporter [16].