HA-1004 is a selective inhibitor of PKA, which can inhibit lipolysis and induce vascular relaxation. HA-1004 is also a dual inhibitor of cyclic GMP-dependent protein kinase and cyclic AMP-dependent protein, and is involved in smooth muscle, second messenger, cyclic AMP and cyclic GMP regulation mechanisms. HA-1004 is an antagonist for calcium, that can be used as a vasodilator to inhibit the contraction of rabbit aortic strips, or to antagonize ERK and tyrosine hydroxylase (TH) phosphorylation in morphine abstinence rat models[1][2][3].