Tangled webs: evidence of cross-talk between c-Raf-1 and Akt.

The apparent cross-communication that can occur between different cell signaling pathways indicates that some signaling mechanisms may be more complex than originally envisaged. Jun et al. discuss recent studies suggesting that two signaling pathways that can be activated by the same growth factor receptor, the Ras-Raf pathway and the phosphatidylinositol 3-kinase (PI3K)--Akt (protein kinase B) pathway, can integrate with each other to generate a particular response, depending on the cell type and the stage of cell differentiation.