FSTL1 and renal fibrosis: Conversely, overexpression of hormones such as brain natriuretic peptide 29 and Follistatin‐like 1 (Fstl‐1) secreted by heart, attenuated renal fibrosis and cardiac‐specific Fstl‐1 knockout mice exhibited exacerbation of renal injury after subtotal nephrectomy 39.