An expression library was made from BMS2.4 cells. Approximately 1.2 × 10⁵ clones were screened on the basis of growth inhibition of 1A9-M cells as described in Materials and Methods, and 6 clones were isolated. Plasmids from each positive clone were transfected into 293T cells, and supernatants of the transfectants were collected after 3 days of incubation. 1A9-M cells were cultured with or without the supernatants for 3 days, and recovered viable cells were measured by hemocytometer. The nucleotide sequences of the inserts from the single clones were determined using an automated DNA sequencer.