ANGPT4 and colitis: Vitamin D-deficient mice treated with DSS had more severe colitis, ↓ colonic Ang4 expression, ↑ bacterial infiltration compared to mice with normal diet; DSS-treated vitamin D-deficient mice had ↓ serum vitamin D level (2.5 ± 0.1 ng/mL) compared to mice with normal diet (24.4 ± 1.8 ng/mL)