Increased expression of the src proto-oncogene in hairy cell leukemia and a subgroup of B-cell lymphomas

The c-src proto-oncogene encodes a M r 60 000 phosphoprotein, pp60 c-src , with tyrosine-specific protein kinase activity. We have used an immune complex protein kinase assay for pp60 c-src to analyze a spectrum of B-cell neoplasms. pp60 c-src activity was elevated in all five hairy cell leukemia specimens and in a number of the large cell and immunoblastic lymphomas; neoplasms representing later stages in B-cell development. pp60 c-src activity was low in neoplastic cells which correspond to early and intermediate stages in B-cell development (acute and chronic lymphatic leukemia, lymphoblastic lymphoma, small lymphocytic lymphoma)