PROS1 and schizophrenia: Even though it was not determined in this study if deficiency was inherited or acquired, low levels of free-protein S increased the chances of having a first-degree relative with schizophrenia by 145 times compared to controls, which suggests that, at least in some of the patients, protein S deficiency could have been inherited.20 Aside from having anticoagulant activity, free-protein S accelerates neutralization of PAI-1, and therefore increases fibrin clot lysis.