Activation of phosphatidylinositol-3' kinase by Src-family kinase SH3 binding to the p85 subunit.

Engagement of antigen receptor complexes induces rapid activation of Src-family kinases and association with phosphatidylinositol-3' kinase (PI-3 kinase). Here it was found that the Src homology 3 (SH3) domain of Lyn and Fyn bound to a proline-rich region (residues 84 to 99) within the 85-kilodalton subunit (p85) of PI-3 kinase. The binding of SH3 to the purified kinase led to a five- to sevenfold increase in the specific activity of PI-3 kinase.

Human tissues as source of colony-stimulating factor in human bone marrow cultures.

Human bone marrow cells were cultured by the agar method using feeder layers containing human tissue fragments of various origin. Colony stimulating factor (CSF) was shown to be released from all tissues tested (adipose tissue, skeletal muscle, peritoneum and vascular wall), and primary cultures of human fibroblasts could also stimulate colony growth. Colony growth of murine bone marrow cells was also stimulated by all feeder layers.