Western blotting with the MUM1p monoclonal antibody.

(A) A band of 52-kd of the expected size of the MUM1-HA protein is seen in line corresponding to pHeBo-CMV-MUM1-HA HeLa-transfected cells but not in negative control HeLa cells. (B) A 50-kd band of the expected molecular size of the MUM1 protein is seen in lanes 2 and 4, corresponding to the IM9 myeloma cell line and normal tonsil. No bands are detected in lanes 1 and 3, corresponding to U937 and HeLa cell lines. Identical results (not shown) were obtained with the monoclonal (clone MUM97) and polyclonal anti-IRF4/ICSAT antibody. In both experiments, β tubulin levels are shown below to control for the integrity and amount of the loaded protein.