Remarkably, in both human and murine PCs, GPI inversely correlated with immunoglobulin expression: Ig transcription progressively declined from normal PCs, to MGUS – or monoclonal gammopathy described in two recent mouse models based on Ikk2ca activation in germinal center B cells -30,31, to newly diagnosed MM – or de novo Vk*MYC or the Ikk2ca crosses -, to relapse/refractory MM – or transplant Vk*MYC or 5TGM1 MM - to human or murine PC lines that grow in vitro, which generally lack Ig expression (Fig. 5B, C). Here, MYC is linked to monoclonal gammopathy.