The invention provides a process for preparing a plurality of modified milk growth factors which process includes: providing a milk product extract including a plurality of milk growth factors having basic to approximately neutral isoelectric points and a source of acid; subjecting the milk product extract to transient acidification utilising the acid source; and isolating a plurality of modified milk growth factors from the transiently acidified milk product extract. Also provided are growth promoting compositions, cell culture compositions, and pharmaceutical or veterinary compositions for the treatment of surface wounds, gastrointestinal injuries, diseases or ulcers, each including a plurality of modified milk growth factors having isoelectric points above approximately 6.0 and molecular weights in the range of approximately 5000 to 30.000, the milk growth factors being modified by transient acidification.