Abstract: The invention relates to cDNA libraries obtained from Tammar wallaby (Macropus eugenii) mammary gland tissue at different times (including day 23 pregnancy, day 130 lactation, and day 260 lactation). Lactation-associated polypeptides were identified from these cDNA libraries, and bovine homologues of the wallaby proteins are also disclosed. The proteins have a range of activities including anti-apoptotic activity, pro- or anti-inflammatory activity, cathelicidin anti-microbial activity, induction of trefoil proteins (and protection of epithelial surfaces), increased cell proliferation, and induction of cell differentiation (and loss of pluripotency).