Egf Knockout mouse — lung specific context

Egf, mouse ortholog of human EGF, encodes not a simple 53 residue peptide but a large transmembrane precursor containing nine EGF-like repeats, from which the mature ligand is liberated by ADAM10 and ADAM17 mediated ectodomain shedding, a regulated step that determines autocrine and paracrine availability. Mature EGF binds EGFR domains I and III with high affinity, stabilizing the extended conformation that exposes the dimerization arm and triggers asymmetric kinase dimer formation, and unlike TGF alpha it remains bound at endosomal pH and thereby routes receptor toward lysosomal degradation rather than recycling, a trafficking distinction with real signaling duration consequences. Null mice are viable with mild epithelial and renal phenotypes because Tgfa, Areg, Hbegf, Btc, Ereg and Epgn all engage the same receptor, so single deletion is nearly uninformative and compound ligand alleles are essential. Use conditional nulls when asking about a specific stromal or epithelial source, and reserve ligand humanization for antibody and ligand trap pharmacology.

A conventional Egf knockout removes gene function in all cells that inherit the allele. It is a proven first pass for target validation when redundancy is low. For lung work, plan Cre specificity, reporter crosses, and baseline phenotyping before you scale.