High Notch1, Notch2, and Jagged1 expression in cultured MM cells. Western blot analysis of cell lysate proteins from cultured MM cells (RPMI-8226, OPM-2, LP-1, NCI-H929, U266; panels A-C, lanes 1-5), mature CD19⁺ B cells (panel A, lane 7; panel B, lane 6), CD38⁺/CD19⁺ plasmablastic cells (panel A, lane 8; panel B, lane 7), and the Hodgkin cell line KM-H2 (panel A, lanes 6 and 9), showing expression of Notch1 (A) and Notch2 (B) as full-length proteins (300 kDa) and their major cleavage product (N™, 110 kDa). In panel A, lanes 1-6, and panels B and C, 30 μg proteins were loaded. In panel A, lanes 7-9, 12 μg proteins were loaded. In panel A, lanes 1-6, proteins were incubated with mouse monoclonal anti-Notch1 antibodies (BD Biosciences); and for lanes 7-9, proteins were incubated with rat monoclonal anti-Notch1 antibodies (bTAN20; Developmental Studies Hybridoma Bank). (C) Expression of the Notch ligand Jagged1 (about 130 kDa) in cultured MM cells (left margin). Size markers are in kilodaltons, and n.s. indicates not significant.