We observed that MG132, but not 3-MA, enhanced the protein level of INSIG1, and the ubiquitylation level of INSIG1 was increased in CRC cells with circINSIG1 or circINSIG1-121 overexpression, indicating that circINSIG1-121 facilitated INSIG1 degradation through the ubiquitin-proteasome pathway (Fig. 4E F). This evidence concerns the gene INSIG1 and colorectal carcinoma.