Figure 1. ERMS caused by activation of the Sonic Hedgehog pathway in the aP2 lineage.

(A) Schematic of the conditional Smo^M2 allele and aP2-Cre mediated recombination.

(B) Gross view of tumors in aP2-Cre;Smo^M2 mice.

(C) Kaplan-Meier survival curves illustrated tumor-free survival of aP2-Cre;Smo^M2/+ mice (blue line, n = 47) compared to Smo^M2/+ littermate controls (red line, n = 19) (p = <0.0001).

(D) Cross-sectional histology of tumors with H&E staining. Arrow points to rhabdomyoblast and arrowhead points to strap cell. (E) Masson’s trichrome. (F-I) Sections of tumors immunostained with Ki67, a marker of proliferating cells (F), and Desmin (G), MyoD1 (H), and Myogenin (I), diagnostic of ERMS. Scale bar = 50 μm (D,E,G-I) and 200 μm (F). See also Figure S1.