Figure 3: HPLC analyses of relative changes in intra- and extracellular gemcitabine levels following pharmacologic efflux inhibition. Pretreatment with probenecid before gemcitabine treatment resulted in significant increases in intracellular gemcitabine levels in H1437, H1792, SU86 and MDA-MB-231 cells (p<0.05) while extracellular gemcitabine levels increased (p<0.05) or remained unchanged; statistically significant values are presented (n=3).