A-3 Hydrochloride is an inhibitor of PKA (cAMP-dependent protein kinase, Ki=4.3μM) and cGMP-dependent protein kinase, Ki=3.8μM, PKC (protein kinase C, Ki=47μM), casein kinase I and II, and MLCK (myosin light chain kinase) ( Ki=7.4μM).
Naphthalenesulfonamides as calmodulin antagonists and protein kinase inhibitors: M. Inagaki, et al.; Mol. Pharmacol. 29, 577 (1986)