HDAC1 and acute respiratory distress syndrome: Further, ELISA results displayed that after overexpression of HDAC1 or silencing of PP2A in the PU-treated ALI mice, elevated levels of TNF-α, IL-1β, INF-γ, and IL-6 were observed (Fig. 5F), indicating that overexpressed HDAC1 or silenced PP2A curbed the alleviation of inflammatory responses by PU in the lung tissues of mice.