Immunofluorescence analysis of MRP and P-glycoprotein expression. U-A10 cells were fixed/permeabilized in ethanol, blocked with goat serum, incubated with polyclonal antibody MRP-6KQ (A and B) or MoAb C219 (C and D), and then exposed to an FITC-conjugated second step. Cells were examined by fluorescence microscopy and photographed. Shown are photographs of typical single cells that are centered within the frame.