HAS1 and inflammatory bowel disease: Although the correlation between the increased expression of these two salivary proteins and the presence of ulcerative colitis does not imply causation, additional sporadic studies have shown significant upregulation of nicotinamide phosphoribosyltransferase [39] and hyaluronan synthase 1 [40] in intestinal biopsies from patients with inflammatory bowel disease, corroborating our correlation analysis.