HDAC4 and pulmonary fibrosis: As explained in Figure 6, the current study’s alternate hypothesis was that PIC, Vit D, or PIC-Vit D would have antifibrotic effects against pulmonary fibrosis through alterations in the levels of expression of HDAC2, HDAC4, and TGF-β in the lungs, and this in turn could inhibit the PI3K/AKT signaling pathway via their antioxidant properties.