L. Varticovski, B. Drucker, D. Morrison, L. Cantley, T. Roberts, "The colony stimulating factor-1 receptor associates with and activates phosphatidylinositol 3-kinase," Nature, 342:699-702, 1989.
Lyuba Varticovski (St. Elizabeth's Hospital, Boston): "We have determined that activation of the colony stimulating factor-1 (CSF-1) receptor results in activation of phosphatidylinositol 3-kinase (PI 3-kinase). PI 3-kinase is a recently discovered enzyme that phosphorylates phosphatidylinositol in position 3 of the inositol ring to produce a series of novel 3 phosphorylated inositol-containing phospholipids. Mutational analysis indicates that activation of PI 3-kinase is essential for growth and transforming ability of several protein-tyrosine kinases. Our study indicates that growth factors of the protein-tyrosine kinase family can activate a novel pathway for generation of second messengers that is distinct from the canonical phosphatidylinositol turnover."