The insulin-like growth factor (IGF) pathway is a key signal transduction pathway involved in cell proliferation, migration, and apoptosis. In dairy cows, IGF family proteins and binding receptors, including their intracellular binding partners, regulate mammary gland development. IGFs and IGF receptor interactions in mammary glands influence the early stages of mammogenesis, i.e., mammary ductal genesis until puberty. The IGF pathway includes three major components, IGFs (such as IGF-I, IGF-II, and insulin), their specific receptors, and their high-affinity binding partners (IGF binding proteins [IGFBPs]; i.e., IGFBP1–6), including specific proteases for each IGFBP. Additionally, IGFs and IGFBP interactions are critical for the bioactivities of various intracellular mechanisms, including cell proliferation, migration, and apoptosis. Notably, the interactions between IGFs and IGFBPs in the IGF pathway have been difficult to characterize during specific stages of bovine mammary gland development. In this review, we aim to describe the role of the interaction between IGFs and IGFBPs in overall mammary gland development in dairy cows.

• Woo Tae Ha(Dept. of Stem Cell and Regenerative Biology, College of Animal Bioscience and Technology, Konkuk University, Seoul 143-701, Korea)
• Ha Yeon Jeong(Dept. of Animal Resources Development Dairy Science Division, RDA, Cheonan 331-801, Korea)
• Seung Yoon Lee(Swine Consulting Group, HanByol Farm Tech, Gyeonggi 463-785, Korea)
• Hyuk Song(Dept. of Stem Cell and Regenerative Biology, College of Animal Bioscience and Technology, Konkuk University, Seoul 143-701, Korea) Corresponding author