Injection of recombinant human CXCL12 protein has been shown to reduce fibrosis in rodent models of chronic kidney disease (28), uterine fibrosis (30), stress urinary incontinence (33, 34), and non-human primate models of intrinsic sphincter deficiency (35, 36) and erectile and urinary dysfunction post-radical prostatectomy (37), but its effects on collagen content and collagen fiber histomorphometry have not been tested in cat models of chronic renal fibrosis. The gene discussed is CXCL12; the disease is chronic kidney disease.