Blockade of VLA-4 or α_vβ₃ integrin suppressed MM cell growth enhancement by OCs. U266 cells (2 × 10⁵/mL) were cultured in alpha-MEM containing 1% FBS in the presence (closed bars) or absence (open bars) of PBMC-OCs (1 × 10⁴/mL) in 24-well culture plates in quadruplicate. Neutralizing antibodies against VLA-4 or α_vβ₃ integrin or control IgG were added at 20 μg/mL to the indicated wells. Viable cell number was counted by trypan blue staining at day 4. The data are expressed as means ± SD. *Significantly different by one-way ANOVA with Scheffe post hoc tests, P < .05.