Macrophage infiltration and inflammatory cytokines are powerful drivers of tumorigenesis and metastasis. Wu et al., in this issue of Cancer Cell, show that TNFalpha-dependent NFkappaB activation induces COP9 signalosome-mediated inhibition of GSK3beta and the SCF(beta-TRCP) ubiquitin ligase, thus leading to stabilization of the transcription factor Snail and promoting cell migration and metastasis.