CST3 and chronic kidney disease: Iron therapy improved kidney function, assessed by serum creatinine, BUN, serum cystatin C, and urine ACR (Figure 4A) and attenuated kidney fibrosis in mice with CKD, as indicated by reduced collagen deposition (Figure 4B) and reduced expression of kidney fibronectin and α-SMA in iron-treated compared with untreated CKD mice (Figure 4C).