PTCH1 and enthesopathy: Vdrf/f;ScxCre+ entheses have an expansion of SafO+ HECs with increased immunoreactivity for BMP and IHH signaling markers p-SMAD1/5/8, PTCH, and RUNX2, and increased ALP activity (Figure 7, B and C), as confirmed by quantitation of the percentage of positive cells for these markers, thereby demonstrating that 1,25D acts directly on Scx+ cells to suppress BMP and IHH signaling and enthesopathy development.