Jagged1-induced Notch target gene activation in MM cells. (A) Cocultivation of HtTA-jag10 cells expressing the Notch-ligand Jagged1 under tetracycline control¹¹  (induction of Jagged1 expression by tetracycline withdrawal) and MM, Hodgkin, and Burkitt lymphoma cell lines expressing various amounts of endogenous Notch1 and Notch2 receptors. RT-PCR analysis showed increased levels of endogenous Hes-1 transcripts in cultured MM cells (RPMI-8226, OPM-2, LP-1) and in the Hodgkin lymphoma cell line KM-H2 after activation by Jagged1. KM-H2 cells served as a positive control. (B) Strong induction of Notch signaling by Jagged1 in primary MM cells.