MLN3897 inhibits MM cell migration and adhesion to OCs. (A) CCL3, CCL5, IL-6, and VEGF secretion was assessed by ELISA in OC supernatants at 48 hours; means (± SD) of 3 independent experiments are expressed as pg/mL on a logarithmic scale. (B) Effects of MLN3897 on cell migration triggered by 48-hour OC supernatants, assessed by Transwell migration assay. INA6 and MM1.S cell lines were preincubated with MLN3897 (10 nM for 4 hours) and seeded in the upper chamber of the Transwell plate. After 4 hours, cells that migrated to the lower chamber were counted. Results are expressed as fold increase over control. (C) Adhesion assay was performed seeding calcein-labeled INA6 and MM1.S cells on OCs (10 000 cells/well) or fibronectin (FBN; 20 μg/mL) in the presence or absence of MLN3897. After 6 hours, nonadherent cells were washed off, and fluorescence intensity of adherent cells were expressed as fold increase over control. (D) Representative CCR1 expression on mature OCs from 3 different donors, analyzed by flow cytometry. Results are expressed as MFI (± SD) of CCR1 and isotype control (IC) from more than 3 independent experiments.