Because of Maf loss in the liver endothelium (Fig. 1A, upper panel), we detected significantly increased deposition of extracellular matrix proteins, as assessed by Sirius red staining of liver samples, mainly located in midzonal areas of the liver, i.e. perisinusoidal liver fibrosis (Fig. 1A, lower panel). The gene discussed is MAF; the disease is Hepatic fibrosis.