Coculture experiments with myeloma cell lines and hOB cells, with the following coculture conditions: (1-3) JJN-3 in upper chamber of tissue inserts and hOB in the lower chamber, (1) with no addition, (2) in the presence of 1:1000 of rabbit anti-HGF serum, or (3) preserum. (4-6) Coculture with physical contact between JJN-3 and hOB, (4) with no addition, (5) or in the presence of 1:1000 of rabbit anti-HGF serum, and (6) preserum. (7) Coculture with physical contact between OH-2 cells and hOB and (8) hOB incubated in the absence of other cells. Supernatants were harvested after 48 hours and IL-11 was measured in duplicates by ELISA. Data are means ± SD from 1 representative experiment of 3.