The Ras and JAKs-STATs signaling pathways after growth factors and cytokines activating their receptors respectively are briefly reviewed. The signal transduction of most growth factors' receptors with intrinsic tyrosine kinase activities is achieved through Ras protein pathway.Otherwise, members of JAKs and STATs superfamilies mediate the signaling process of cytokines' receptors lacking intrinsic tyrosine kinase activities. Studies on the signal transduction of growth factors and cytokines are becoming the important subjects in researches of life sciences.