We are also interested in understanding the regulation of thrombosis by 5-HT and SERT. Mutations in the promoter region of the SERT gene regulate transporter expression and are associated with risk for depression after a stressful event. Besides altering lifestyle choices, which may place patients in high risk for coronary disease, depression is also associated with changes in platelet expression of proaggregatory markers. Depressed patients show elevated expression of P-selectin and GPIIbIIIa (integrin αIIbβ3) that are normalized after treatment of symptoms with selective serotonin reuptake inhibitors (SSRIs). This suggests that inhibition of SERT may itself be protective against thrombosis. Here we test the hypothesis that SERT expression levels influence the expression of proaggregatory proteins, specifically of GPIIbIIIa.