The mechanisms mediating and regulating assembly and disassembly of intercellular junctions is a subject of intensive research. The IgG autoantibodies produced in patients with the immunoblistering skin disease pemphigus vulgaris (PV) can induce keratinocyte (KC) dyshesion (acantholysis) via mechanisms that involve signaling kinases targeting intercellular adhesion molecules, thus providing a useful model to study the physiologic regulation of KC cohesion. Previous studies showed that activation of Src and protein kinase C are the earliest events in the PV IgG-induced intracellular phosphorylation cascades, and that cholinergic agonists are effective for treating patients with pemphigus. In this study, we sought to elucidate the molecular mechanisms allowing cholinergic agonists to inhibit PV IgG-induced acantholysis and phosphorylation of KC adhesion molecules. The extent of acantholysis in KC monolayers correlated closely with the degree of PV IgG-induced phosphorylation of p120- and -catenins, with classic isoforms of protein kinase C mediating serine phosphorylation of -catenin and Src—tyrosine phosphorylation of p120-catenin. The M₁ muscarinic agonist pilocarpine blocked phosphorylation of both catenins and the 7 nicotinic agonist AR-R17779—that of p120-cateinin, which could be abolished by the M₁ antagonist MT7 and the 7 antagonist methyllycaconitine, respectively. Okadaic acid abrogated protective effects of agonists on phosphorylation of -catenin, and pervanadate—on that of p120-catenin. Stimulation of KCs with pilocarpine significantly (p<0.05) elevated both serine/threonine and tyrosine phosphatase activities in KCs. AR-R17779 both stimulated tyrosine phosphatase and decreased PV IgG-induced Src activity. Methyllycaconitine released Src activity in intact KCs, and caused acantholysis. Thus, downstream signaling from M₁ abolished PV IgG-dependent catenin phosphorylation due to activation of both serine/threonine and tyrosine phosphatases, whereas 7 action involved both activation of tyrosine phosphatase and inhibition of Src. These findings identified novel paradigm of regulation of signaling kinases associated with cholinergic receptors, and provided mechanistic explanation of therapeutic activity of cholinomimetics in PV patients.