AXII and AXIIR are involved in the adhesion of MM cells. (A) Ninety-six–well plates were coated with the indicated concentrations (μg/mL) of AXII or BSA by incubating overnight at 4°C. The next day, MM1.S cells were added to AXII or BSA-coated plates and the percentage of change in binding of MM1.S cells to the AXII or BSA-coated plates was assessed relative to uncoated plates. (B) Calvarial OBL (10⁴) from AXII^+/+ or AXII^−/− mice were plated in 96-well plates in 100 μL of α-MEM containing 10% FCS and incubated overnight at 37°C. The next day, cells were washed with PBS and fluorescent-labeled MM cells were added to the OBL. The plates were centrifuged at 52g for 5 minutes and placed in the dark for 15 minutes. The background fluorescence was measured with a plate reader. The cells were washed with PBS and read again to determine the percentage of adherence. (C) Calvarial OBL (10⁴) from AXII^+/+ mice were plated in 96-well plates in 100 μL of α-MEM containing 10% FCS and incubated overnight at 37°C. The next day, cells were washed with PBS and fluorescent-labeled MM cells were added to the OBL. Control IgG and anti-AXII were added to some of the wells. The plates were centrifuged at 52g for 5 minutes and placed in the dark for 15 minutes. The background fluorescence was measured with a plate reader. The cells were washed with PBS and read again to determine the percentage adherence. (D) Forty-eight– well plates were coated with AXII (1 μg/mL) by incubating plates overnight at 4°C. The next day, MM1.S cells were added to the plate and incubated at 37°C for 2 hours. AXIIR Ab (rabbit) or a control IgG (1 μg/mL) was included in a set of wells. At the end of 2 hours, the nonadherent MM1.S cells were counted. (*P < .05; **P < .01; ***P < .001).