The LTF gene (lactoferrin gene) encodes a multifunctional iron-binding glycoprotein that belongs to the transferrin family. It is mainly expressed in mucosal secretions (such as milk, tears, saliva), neutrophils, mammary gland, and the epithelial cells of the respiratory and gastrointestinal tract, and is particularly abundant in milk. This gene is often used as a marker for mammary epithelial cells and some immune cells. The Ltf-iCre mice are obtained by integrating the Kozak-iCre-P2A expression cassette upstream of the start codon of the endogenous Ltf gene in mice through gene editing technology. Under the drive of the regulatory elements of the mouse Ltf gene, the iCre recombinase (a codon-optimized Cre recombinase) is expressed.