The Centre for Cellular and Molecular Biology here has developed India's first "gene knockout' mouse which cannot produce milk. With his development, India has joined the select list of nations which have carried out similar experiments. The CCMB scientists achieved it by manipulating a milk-producing gene in the mouse that usually secretes the milk protein kappa casein. The mouse can produce mice but cannot secrete milk for them. Milk production is one of the distinguishing characters that separate mammals from other animals.