Secretion of whey acidic protein and cystatin is down regulated at mid-lactation in the red kangaroo (Macropus rufus) - Nicholas, K.R.; Fisher, J.A.; Muths, E.; Trott, J.; Janssens, P.A.; Reich, C.; Shaw, D.C. (Comparative Biochemistry and Physiology, Part A: Molecular & Integrative Physiology, 2001)