New molecules from caterpillars and ticks are being explored in our laboratory as anticoagulant, defibrinogenant or antitumoral agents. From Lonomia obliqua bristles´ extract two native proteins were characterized: Lopap (a prothrombin activator) and Losac (a FX activator), moreover a cDNA library was constructed and the r-Lopap was cloned and expressed. Losac it is a 45 kDa single chain protein which cleaves the FX heavy chain resulting in the FXa and this enzymatic activity is abolished by serine protease inhibitors; r-Lopap is able to activate prothrombin by generating prethrombin-2, F1.2 and thrombin and its enzymatic activity is also abolished by serine protease inhibitors; in vivo assays showed that the infusion of r-Lopap promotes defibrinogenation and unclottability in mice. Both proteins (r-Lopap and Losac) where assayed on HUVECs and they are able to modulate the cell survival by preventing apoptosis, Losac increase NO and induces t-PA expression. The mechanism of proliferation of HUVECs by Losac is not clear, but our results suggest that t-PA and NO may be involved. On the other hand, r-Lopap modulates the expression of Bcl-2 genes family and increases NO and PGI2 concentrations, besides, the collagen secretion was observed in the cells treated with r-Lopap. A protein classified as Serpin-like was cloned from the Amblyomma tick salivary glands and the recombinant inhibits FXa and promotes the melanoma cells apoptosis in vitro and in vivo. The goal for the moment is to improve the up scale proteins production to perform pre clinical tests. Supported by FAPESP, CNPq, COINFAR