Tyrosine kinases, Src and spleen tyrosine kinase (Syk), play crucial roles in cell responses to platelet-derived growth factor (PDGF) and may have their functional interactions. In this study, we focused on investigating the roles of Syk in the regulation of Src signaling in PDGF-mediated vascular cell responses. Migration, proliferation, and activity of kinases were determined in rat aortic smooth muscle cells (RASMCs). PDGF-BB (10ng/mL) induced the migration and proliferation of RASMCs, which were significantly inhibited by PP2 (10 ${mu}$M) and piceatannol(30 ${mu}$M), inhibitors of Src and Syk, respectively. The phosphorylation of Syk induced by PDGF-BB was abolished by PP2. PDGF-BB increased the co-association of the PDGF${eta}$-receptor and the kinases, Src or Syk, and its maximal binding to Src was achieved in a shorter time than that to Syk. PDGF-BB stimulated the phosphorylation of p38 mitogen-activated protein kinase(MAPK) and extracellular signal-regulated kinase (ERK) 1/2, which was inhibited by PP2 and piceatannol. PDGF-BB-induced proliferation and migration were inhibited by SB203580 (30${mu}$M) and PD98059 (30 ${mu}$M), inhibitors of p38 MAPK and ERK1/2, respectively. These result simply that Syk is regulated by Src kinase, which participates in migration and proliferation in response to PDGF-BB in RASMCs.