EIF3K and tropical spastic paraparesis: M9 is a bipartite phenylalanine-tyrosine nuclear localization sequence (PY-NLS) that requires binding to TPNO-1 for hnRNP A1 to shuttle between the nucleus and cytoplasm16,31 Because of the similarities between MS and HAM/TSP, we hypothesized that MS patients would also develop antibodies to hnRNP A1.