A, GP and GR epithelial tumor cells are equally responsive to gefitinib. A, GP and GR epithelial tumor cells are equally responsive to gefitinib. Equal numbers of GP and GR epithelial tumor cells seeded in 96-well plates were treated in quadruplicates with increasing concentrations of gefitinib (0, 0.1, 1, 5, 10, and 20 μmol/L) for 5 d. End point cell viability was measured using the MTS assay, and the data are represented as a percentage of the nontreated sample. B, same as in A, except cells from 60-mm dishes were lysed and analyzed by immunoblot for pEGFR, EGFR, pMAPK, and β-actin. C, hEMP-1 is expressed in the GR CAFs. Quantitative RT-PCR analysis of hEMP-1 mRNA comparing GP to GR in the tumor tissue, epithelial tumor cells, and CAFs. Data are normalized to GAPDH and presented as fold induction of GP tumor tissue. D, FISH analysis of purified GP and GR CAFs with CEP Y (DYZ1) probe (green fluorescent signal) depicting human nuclei (white arrow) and murine nuclei (red arrow). Nuclear counter staining with DAPI (blue). Sheldon R. Mink et al. Mol Cancer Res 2010;8:809-820 ©2010 by American Association for Cancer Research