Stromal cells (i) release Gal1 able to expand CD45– MM cells at the expense of CD45+ MM cells; (ii) express and release RankL, a potent activator of OC, and (iii) release activin A, a contraIL6 and inhibitor of OB, contraI IGF1R by themselves (stromal activin A twice in favor of IGF1 at the expense of IL6). This evidence concerns the gene IGF1 and Miyoshi myopathy.