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One of the flavones, apigenin has various physiological functions including anti-inflammatory activities. Atopic dermatitis (AD) is a chronically relapsing inflammatory disorder that is characterized by pruritic and eczematous skin lesions. To evaluate the anti-allergic effect of apigenin in vivo, we examined the effect of dietary apigenin on picrylchloride (PiCl)-induced AD-like pathology in NC/Nga mice. NC/Nga mice were fed experimental diets containing apigenin from Day 18 after sensitized with PiCl for 4 weeks. Dietary apigenin significantly alleviated the development of skin lesions, accompanied by lower serum immunoglobulin (Ig) G1 and IgE levels in NC/Nga mice. Interferon (IFN)-gamma mRNA expression level in spleen cells from NC/Nga mice was reduced by apigenin feeding. Moreover, interleukin 4-induced signal transducers and activators of transcription 6 phosphorylation in primary spleen cells from BALB/c mice was inhibited by treatment with apigenin. These results suggest that apigenin attenuates exacerbation of AD-like symptoms in part through the reduction of serum IgE level and IFN-gamma expression in NC/Nga mice.

H89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide) is a compound characterized in vitro as a potent and selective inhibitor of protein kinase A (PKA). In this study, we found that H89 reduced the phosphorylation of the myosin regulatory light chain (MRLC) at Thr-18/Ser-19 and induced disassembly of stress fibers in HeLa cells. In addition, we found that H89 induced not only reduction of the MRLC phosphorylation but also cell growth inhibition in several human cancer cell lines. Recently H89 has been found to inhibit Rho-kinase with potency similar to or greater than that for inhibition of PKA. Indeed, the effects of H89 on both the MRLC phosphorylation and actin cytoskeleton organization were nearly identical to those of Rho-kinase inhibitor Y-27632. However, unlike H89, Y-27632 did not affect cell growth of HeLa cells. Further, when the myosin phosphatase targeting subunit 1 (MYPT1) expression was silenced by RNA interference in HeLa cells, the suppressive effect of H89 on the MRLC phosphorylation was not affected, while H89-induced cell growth inhibition was blocked. These results suggest that H89-induced reduction of the MRLC phosphorylation results from inhibition of Rho-kinase and that H89-induced cell growth inhibition is independent of reduction of the MRLC phosphorylation.