JAG1 and Miyoshi myopathy: Homotypic, or autonomous, Jagged1-Notch1 interactions between MM cells have been shown to increase cell proliferation through the upregulation of the downstream effectors cyclin D1 and D2 as blockade of Notch1 with neutralizing antibodies has been shown to reduce their expression in MM cells (Jundt et al., 2004; Ishibashi et al., 2020).