Fig. 1.

Folate receptor-α (FRα) is necessary for drug uptake, expressed, and accessible in cyst lining epithelial cells. A: KB and A549 cells, representing FRα-positive and -negative cells, respectively, were treated with increasing doses of folate-conjugated rapamycin (FC-rapa) (EC0371) in the absence or presence of excess soluble folic acid (XS FA). The expression of phospho-ribosomal protein S6 (P-S6) was analyzed by immunofluorescence staining and flow cytometry. B: 2-kidney weights relative to whole body weights (BW) demonstrating progression of disease throughout treatment time course. PKD, polycystic kidney disease. C: FRα expression by immunohistochemistry on kidney sections from PKD1^fl/−:Nes^Cre mice versus PKD1^fl/wt:Nes^Cre+ control mice [wild-type (WT)] showing expression in normal tubules and in cyst lining cells. D: renal immunofluorescence staining for folate-conjugated reporter (FC-reporter) 4 h after intraperitoneal injection into wild-type (left), bpk (middle), or PKD1^fl/−:Nes^Cre (right) mice. Animals were injected on postnatal day 12 with either PBS or FC-reporter. Scale bars = 50 μm; red is nuclear stain (DAPI), and green is FC-reporter.