SOCS1 and tropical spastic paraparesis: A very recent study of ex vivo CD4+ cells isolated from 30 HTLV-1-infected individuals (ACs, HAM/TSP, ATLL) demonstrated that SOCS1 (Suppressor Of Cytokine Signaling 1) is strongly up-regulated in ACs and patients with HAM/TSP but not in those with ATLL.