Secreted by the lacrimal gland into tears. Expressed in the lacrimal gland from where it is secreted into tears (at protein level). Expressed at low levels in lacrimal gland of both immature females and males at 10 days of age (at protein level) (PubMed:18703064). At 15 days of age, higher levels are found in males than females (at protein level) (PubMed:18703064). Levels decrease in males after day 20 and there is no expression in males by day 36 (at protein level) (PubMed:18703064). Highly expressed in lactating females when estrogen levels are low (PubMed:15950295, PubMed:9634868, PubMed:10622403). Levels drop by 25 days post-weaning (PubMed:10622403). Repressed by estrogens, androgens and thyroxine in adults (at protein level) (PubMed:7887957, PubMed:9634868, PubMed:10622403, PubMed:17316636). Repression by estrogens and androgens does not occur in immature 20-day old animals (PubMed:18703064). Induced by prolonged light deprivation and starvation (at protein level) (PubMed:10622403). Belongs to the calycin superfamily. Lipocalin family.