IFN-α–induced growth inhibition in MM correlates with enhanced PML expression. (A) Proliferation of MM cell lines H929, 8226, Delta47, and OPM2 following treatment with indicated amounts of IFN-α for 48 hours was determined by MTS assay as described in “Materials and methods.” Data are the average of 3 independent experiments performed in triplicate (±SD). (B) RT-PCR analysis of transcriptional induction of PML mRNA in the indicated MM cell lines with (+) or without (-) IFN-α (2000 U/mL) treatment for 48 hours. The amplified fragment is located at 5′-end and appears in all PML isoforms. The level of GAPDH serves as loading control. (C) Western blot analysis of PML protein isoforms using rabbit polyclonal anti-PML with (+) or without (-) IFN-α (2000 U/mL) treatment for 48 hours. The level of GAPDH serves as loading control.