ATF4 and chronic kidney disease: Additionally, ATF4 actively participates in the phenotype switch of vascular smooth muscle cells (VSMCs) into osteoblast-like cells and subsequent vascular calcification, which notion is supported by the attenuation of CKD-driven aortic calcification in vascular smooth muscle cell-specific ATF4-deficient mice (Masuda et al., 2016; Rao et al., 2022).