In line with the tumor theory, several studies report overexpression and secretome emission of growth factors such as TGF-β, IGF-I, PDGF, and EGF in keloid tissue, with keloid cells demonstrating heightened sensitivity to these factors compared to normal cells (Haisa et al., 1994; Younai et al., 1994; Ohtsuru et al., 2000). Here, IGF1 is linked to keloid.