phosphatase mediated signaling pathway serine/threonine-specific phosphatase mediated signaling pathway PW:0000653 Serine/threonine-specific phosphatase mediated signaling presents an interesting case. If the number of tyrosine kinases and of tyrosine phosphatases is similar (~100 in mammals), serine/threonine kinases have diversified to some 400 members in the course of evolution while the serine/threonine phosphatases count to about 25. The functional versatility is conferred through the diversity of regulatory subunits with which they interact. The holoenzyme dictates the role the protein complex plays in signaling pathways. pathway