Acts as a negative regulator of mTOR activity. Interacts with FBXW5; TNFAIP8L1 competes with TSC2 to bind FBXW5 increasing TSC2 stability by preventing its ubiquitination. High expression detected in most carcinoma cell lines, especially in cells transformed with virus genomes. Up-regulated by oxidative stress (OS) at both transcriptional and translational levels. Belongs to the TNFAIP8 family.