Immunoblot analysis for caspase-6, caspase-9, and DFF45 in myeloma cells exhibiting differential sensitivities to TRAIL.

Immunoblot analysis for caspase-6, caspase-9, and DFF45 was performed for TRAIL-sensitive (MM.1S), moderately resistant (ARH-77), and highly resistant (IM-9) cells treated with TRAIL (300 ng/mL) for 0.5 and 1 hour. Rapid cleavage of caspase-6, caspase-9, and DFF45 was observed in MM.1S, but not ARH-77 or IM-9 cells. A band corresponding to cleaved caspase-9 was constitutively present in ARH-77 or IM-9 cells, but remains unchanged after TRAIL treatment.