src family PTKs are activated in CD45⁺ but not CD45⁻ myeloma cell lines.

(A) Western blot analysis shows the expression of Lyn (p53 and p56), Fyn, Blk, SHP-1, and SHP-2 in the myeloma cell lines indicated. (B) The kinase activity of Lyn or Fyn in myeloma cell lines stimulated with (+) or without (−) IL-6 was investigated by kinase assay using enolase as an exogenous substrate. (C) The immunoprecipitation (IP) and Western blot analysis with the indicated antibodies were used to examine the interaction of Lyn or Fyn kinases with CD45 or gp130 molecules in myeloma cell lines treated with (+) or without (−) IL-6.