Another report demonstrated that FLCN in association with FNIP1 preferentially binds to GDP-bound /nucleotide free Rag A/B under amino acid deprived conditions suggesting a potential role for FLCN as a GEF for RagA/B.
The study suggested that FLCN, working together with FNIP1, has a strong affinity for GDP-bound, nucleotide-free Rag A/B under conditions where amino acids are limited, implying that FLCN might be involved in activating RagA/B.