Mouse Prolactin Receptor (PRLR) is a transmembrane receptor belonging to the class I cytokine receptor family, which also includes receptors for growth hormone (GHR), erythropoietin (EPOR), and several interleukins that signal through related intracellular pathways. In mice (Mus musculus), PRLR binds the hormone prolactin (PRL) and activates intracellular signaling cascades, primarily the JAK2/STAT5 pathway, along with MAPK and PI3K/AKT pathways, leading to regulation of genes involved in cell proliferation, differentiation, and metabolic function. Mouse PRLR is expressed in multiple tissues including the mammary gland, ovary, uterus, liver, adipose tissue, brain, and immune cells, where it mediates the diverse physiological effects of prolactin. PRLR signaling plays a critical role in mammary gland development, lactation, reproductive function, and maternal behavior. In addition to the membrane-bound receptor, soluble forms of mouse PRLR (sPRLR) can be generated through alternative splicing or proteolytic cleavage, producing extracellular receptor fragments capable of binding circulating prolactin and potentially modulating hormone availability and signaling activity. Because mice are widely used as genetic models, PRLR knockout and transgenic mouse models have been extensively utilized to study lactation biology, reproductive endocrinology, immune regulation, and prolactin signaling pathways, providing important insights into hormonal regulation and endocrine function relevant to human physiology and disease.