JAG1 and Miyoshi myopathy: Two ways of Notch pathway activation in MM have been described; MM cells express Notch 1, 2, 3 that can bind to their ligands presented either on the same cells (Jagged 1,2), namely homotypical interaction, or on adjacent BMSCs and malignant plasma cells (Jagged or Delta-like ligands), namely heterotypical interaction30.