proinflammatory cytokine associated with many chronic debilitating diseases such as rheumatoid arthritis and multiple sclerosis tnf u03b1 also induces angiogenesis promotes fibroblast proliferation and can combine with receptors on selected tumor cells to induce cell lysis tace is also implicated in amyloid precursor protein secretion human recombinant tace expressed in sf21 cells r amp d system 930 adb is used test compound and or vehicle is incubated with the enzyme 25 ng ml and 10 u03bcm mca p l a q a v dpa r s s s r nh 2 seq id no 3 in modified tris buffer ph 9 0 for 30 minutes at 25 u00b0 c enzyme activity is determined spectrofluorimetrically by measuring the formation of fluorescent mca p l a q a nh 2 seq id no 4 compounds are screened at 10 u03bcm phosphodiesterase type 3 pde3 partially purified from human platelets is used test compound and or vehicle is incubated with 1 u03bcg enzyme and 1 u03bcm camp containing 0 01 u03bcm 3 h camp in tris buffer ph 7 5 for 20 minutes at 25 u00b0 c the reaction is terminated by 2 minutes boiling the resulting amp is converted to adenosine by.