Hedgehog Pathway Inhibition in Liver Cancer Model Figure 4. Effects of Mdr2 deficiency and Hedgehog (Hh) inhibition on hepatic progenitor populations. A. Immunohistochemical staining of liver sections from representative, age-matched Mdr22/2 and wildtype mice for progenitor markers, cytokeratin-19 (CK-19) (top panels) and a -fetoprotein (AFP) (bottom panels) (206). B. Representative micrograph of a portal triad in liver of an Mdr22/2 mouse, demonstrating co- localization of CK-19 (blue) and Gli2 (brown) in the ductular compartment (406). C. Quantitative Gli2 and CK19 immunohistochemistry in DMSO- and GDC-0449-treated Mdr22/2 mice (n = 9–10/group). The number of Gli2 and CK19 double-positive ductular-appearing cells were counted within tumors under 206 magnification. Mean6SEM double(+) cells t per high power field (HPF) are graphed (* p,0.05) D. QRT-PCR analysis of AFP in tumor RNA from mice treated with DMSO (open bar) or GDC-0449 (closed bar) Results in the GDC-0449-treated mice were normalized to that of the mice treated with DMSO vehicle and graphed as Mean6SEM (*p,0.05). doi:10.1371/journal.pone.0023943.g004 PLoS ONE | www.plosone.org 7 September 2011 | Volume 6 | Issue 9 | e23943