GREM1 and Miyoshi myopathy: In support of this, Western blot analysis revealed that 5TGM1 MM PCs cultured in the presence of Grem1-overexpressing OP9 stromal cells displayed a reduction in BMP-mediated phosphorylation of the Smad pathway, compared to 5TGM1 MM PCs co-cultured with OP9-empty vector control (Figure S2).