GLI1 and neoplasm: Furthermore, stromal cells from KPmTmG mice treated with 5E1 showed ~90% decrease in Gli1 mRNA transcription compared with stromal cells treated with IgG1 control in contrast to FACS-sorted epithelial cells (Fig. 2d), suggesting that the Hh signaling pathway is activated primarily in stroma by a paracrine mechanism with no autocrine activation in tumor epithelia.