Figure 4

Relationship between growth inhibitory effects of paclitaxel, ABCB1 expression and cellular drug accumulation and efflux.

Paclitaxel growth inhibitory effect (IC₅₀) was determined in 13 lymphoblastoid cell lines (a), (c) and (e) and 6 ovarian cancer cell lines (b), (d) and (f) by CellTitre AQueous One Solution Cell Proliferation Assay after 72 hrs drug exposure. ABCB1 mRNA expression (a) and (b) was measured by RT-PCR and bodipy-FL-paclitaxel accumulation (c) and (d) and efflux (e) and (f) were measured by flow cytometry. The correlation between paclitaxel IC₅₀ and ABCB1 expression (a) and (b), paclitaxel IC₅₀ and drug accumulation (c) and (d) and the correlation between IC₅₀ and drug efflux constant K_E (e) and (f) were determined by simple linear regression analysis.