PGP and leukemia: To a certain extent, obacunone had cytotoxicity on ovarian cancer cell SKOV3 (IC50 > 60 μM), skin melanoma cell SKMEL2 (IC50 = 43 μM), central nervous system cell XF498 (IC50 > 60 μM) [20], leukemia cell lines CCRF-CEM cells (IC50 = 33.77 ± 5.46 μM), leukemia cell lines multidrug-resistant P-gp-overexpressing subline CEM/ADR5000 cells (IC50 = 28.99 ± 3.18 μM), U87MG glioblastoma cells (IC50 = 38.47.99 ± 3.20 μM), and EGFR-transfected U87MG.ΔEGFR subline (IC50 = 49.22 ± 2.98 μM) [6].