Dose-dependent inhibition of myeloma cell proliferation by BIBF 1000. (A-C) Myeloma cells (5 × 10⁴) per well were seeded onto 96-well plates and cultured in RPMI-1640 medium with or without BIBF 1000. Cells were pulsed with 0.625 μCi (0.023 MBq) ³H-thymidine per well for 72 hours. Cells were harvested, and ³H-thymidine incorporation was counted. ³H-thymidine uptake is shown as mean values of triplicate determinations from 2 independent series of experiments for each cell line. ³H-thymidine uptake was normalized to the controls without BIBF 1000. A 70% or greater inhibition of proliferation by 1.0 μM BIBF 1000 was observed in the t(4;14)–positive KMS-11, OPM-2, and NCI-H929 cells and in the t(14;16)–positive MM.1S and MM.1R cells (P < .001; BIBF 1000 [1.0 μM] versus control without BIBF 1000). BIBF 1000 (1 μM) inhibited the proliferation of U-266 and L-363 by approximately 50%, whereas it did not or only marginally influence the proliferation of the t(14;16)–positive cell lines JJN-3 and ANBL-6 as well as of the t(16;22)–positive cell line RPMI-8226.