Based on limited published evidence, FHIP1B is a component of the FTS/Hook/FHIP (FHF) complex that functions in vesicle trafficking and endosomal transport. The FHF complex promotes dynein-mediated cargo transport along microtubules and facilitates AP-4 complex distribution to the perinuclear region 1. FHIP1B specifically associates with early endosomes through direct interaction with Rab5-GTP and participates in dynein-dynactin cargo recognition 2. Recent structural studies reveal FHIP1B functions within an autoinhibited FTS-HOOK3-FHIP1B complex that is activated by kinesin-3 KIF1C to enable bidirectional motor codependence 3.