In contrast to the findings with Insig1ΔKap mice, fibroblast deficiency of Insig1 did not worsen UUO-induced renal fibrosis, as evidenced by unchanged collagen deposition and fibrotic indicator (Fn, Acta2, Col3a1, and Vim) mRNA expressions in the kidneys (Fig. 4D,E). This evidence concerns the gene COL3A1 and renal fibrosis.