SEQUENTIAL PROTEIN-KINASE REACTIONS CONTROLLING CELL-GROWTH AND DIFFERENTIATION

Sequential protein kinase reactions involve the phosphorylation and ac tivation of multiple kinases in a pathway. The growth factor receptor tyrosine kinase regulation of the mitogen-activated protein kinase (MA PK) pathway was defined in 1993. The MAPK pathway involves sequential protein kinase reactions. Notable advances were made in defining tyros ine kinase receptor regulation of Ras, and these discoveries were comb ined with the identification of Raf-1, a serine-threonine protein kina se in the MAPK pathway, as an effector for Ras GTP.