Kinetics of Mcl-1, caspases 3, 8, and 9, and Bid cleavage in MDN and KMS12PE. Myeloma cells (3 million/6 mL) cultured with (MDN) or without (KMS12PE) 3 ng/mL IL-6 were treated with 0.6 μg/mL HGS-ETR1 mAb during various times. Western blot analysis was performed as described in “Materials and methods.”