Hh signaling pathway is active in AML. (A) Expression of the Hh pathway components PTCH1, SMO, GLI1, GLI2, and GLI3 was measured by real-time Q-PCR in a panel of 30 clinical specimens from patients with AML. (B) Primary AML blasts were treated with 100 nM of the SMO antagonist PF-04449913 for 48 hours, and proliferation was measured by using XTT (Roche) assay. Results were shown as a percentage of the respective control of each sample. *P < .05 compared with control. (C) Basal SMO, GLI1, and GLI3 protein levels were measured by western blotting. Protein lysates were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotted with GLI3 antibody. GLI3F represents the unprocessed full length GLI3, and GLI3R represents the processed repressor form of GLI3. Glyceraldehyde-3-phosphate dehydrogenase was used as a loading control. (D) Correlation between GLI1 and SMO protein levels in myeloid leukemia cell lines. Protein levels were analyzed by densitometry. The x-axis represents Gli1, and the y-axis represents SMO. (E) Correlation between GLI1 and GLI3R protein levels in myeloid leukemia cell lines. Protein levels were analyzed by densitometry. The x-axis represents GLI1, and the y-axis represents GLI3R.