Retraction: A Novel Carbamoyloxy Arylalkanoyl Arylpiperazine Compound (SKL-NP) Inhibits Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) Channel Currents in Rat Dorsal Root Ganglion Neurons - Chung, Gehoon (The Korean Physiological Society and The Korean Society of Pharmacology, 2012)