Biomedical Science Letters

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Fig. 2.

Effect of 13-cis retinoic acid on nitric oxide synthase activity in human malignant keratinocytes. (A) No regulatory effect of 13-cis retinoic acid on nitric oxide synthase activity. (B) Dose-dependent upregulation of LPS-induced nitric oxide synthase activity by 13-cis retinoic acid. All-trans retinoic acid and 13-cis retinoic acid were added to the culture medium at 0 h of incubation and the NO values were measured at 12, 24, 36, and 48 h. Each value represents the mean ± S.E. of three independent determinations. No significant difference in the level of NO release was found between all-trans retinoic acid and 13-cis retinoic acid treated and control in the absence of LPS. A significant difference in LPS-induced NO productions between the control and all-trans retinoic acid and 13-cis retinoic acid treated samples was indicated by *P<0.01.

Biomed Sci Letters 2019;25:196-200 https://doi.org/10.15616/BSL.2019.25.2.196
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