Aberrant cytoplasmic aggregation of FUS, which is caused by its mutations primarily in the C- terminal nuclear localization signal, is associated with 3% of familial amyotrophic lateral sclerosis (ALS). FUS aggregates are also pathognomonic for 10% of all frontotemporal lobar degeneration cases (FTLD-FUS), however they are not associated with its mutation. This implicates differences in the mechanisms driving inclusion formation of FUS in ALS and FTLD. Here we show that C-terminal tyrosine at position 526 of FUS is crucial for normal nuclear import. This tyrosine is subjected to phosphorylation, which reduces interaction with transportin 1 and may consequentially affect transport of FUS into the nucleus. Furthermore, we show that this phosphorylation can occur through the activity of Src family of kinases. Our study implicates phosphorylation as an additional mechanism by which nuclear transport of FUS may be regulated and potentially perturbed in ALS and FTLD.