CD138+ primary MM cells expressed FGFRs 3 and 4 but not significant amounts of FGFR1, while the cell lines RPMI-8226 and JJN3 expressed FGFRs 1 and 4 (Supplementary Figure S5), predicting that all should be responsive to FGF23. This evidence concerns the gene FGFR1 and Miyoshi myopathy.