CUL5 and colorectal carcinoma: Moreover, circINSIG1 encoded a 121 amino acid protein circINSIG1-121 to promote K48-linked ubiquitination of the critical cholesterol metabolism regulator INSIG1 at lysine 156 and 158 by recruiting CUL5-ASB6 complex, thus inducing cholesterol biosynthesis to facilitate CRC proliferation and metastasis.