Effects of therapeutic administration of the anti-α4 Ab combined with melphalan on serum IgG2b levels and 5TGM1/luc tumor burden in bone. Anti-α4 Ab and melphalan were given as described in Figure 1. Data are mean ± SEM of 2 separate experiments (n = 8 × 2 = 16). ^*Significantly different from control IgG. ^**Significantly different from anti-α4 Ab or melphalan alone.