ERBB3, also known as receptor tyrosine-protein kinase erbB-3, is a member of the epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases. This protein has been shown to implicate in numerous cancers, including prostate, bladder, and breast tumors. Also, it is found in epithelial cell layers of gastrointestinal, reproductive, urinary, endocrine and nervous systems, skin and muscle. ERBB3 has different isoforms derived from alternative splicing variants, and among which, the secreted isoform lacking the intermembrane region modulates the activity of membrane-bound form. Recombinant mouse ERBB3, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.