Gene expression of several myeloma cell growth factors. (A) Affymetrix APRIL, IGF-1, IL-10, BAFF, and IL-6 gene expression in BM CD34 cells (n = 5), BM stromal cells (n = 5), purified BM CD15 (n = 5), CD14 (n = 5) and CD3 cells (n = 5), osteoclasts (n = 7), normal memory B cells (n = 6), normal polyclonal plasmablasts (n = 7), normal BMPCs (n = 7), and purified myeloma cells from patients with MM (n = 131). (B) The concentrations of BAFF, APRIL, IL-10, IL-6, or IGF-1 were assayed with an enzyme-linked immunosorbent assay in 3-day culture supernatant of XG-1 and XG19 cells, osteoclasts, and XG-1/osteoclasts and XG-19/osteoclast cocultures. Results are the mean value of 3 independent experiments.