We previously reported that S-allyl-L-cysteine (SAC)-induced cell proliferation was involved in intracellular insulin-like growth factor (IGF)-I secretion via the Janus kinase 2 (JAK2) / phospholipase C (PLC) pathway in primary cultures of adult rat hepatocytes. Furthermore, we demonstrated that growth hormone (GH) stimulates the GH receptors in cultured hepatocytes to promote IGF-I secretion through the JAK2/PLC pathway. In this study, we investigated whether SAC binds to GH receptors by examining the affinity between the anti-GH receptor monoclonal antibody (anti-GHR mAb) and GH receptors in the presence of SAC or GH using a GH receptor immunofluorescence technique (GH receptor imaging). The GHR in hepatocytes emitted a fluorescent signal when labeled with a fluorescent dye-coupled anti-GHR mAb. Interestingly, SAC-treated fluorescent signals tended to decrease compared to the absence of SAC, and this effect was dependent on SAC doses. A similar trend was observed in GH treatment. In contrast, S-methyl-L-cysteine, which is a structural analog of SAC and has no hepatocyte proliferation capacity, did not show any decrease in fluorescence intensity. These results indicate that SAC shares the same binding site as GH for the GH receptor. In other words, SAC induces JAK2 phosphorylation by binding to GH receptors expressed on the hepatocyte membrane.