Rabll-FIP4 is a member of the Rab 11-Family of Interacting Proteins (FIPS') and is also known as arfophilin 2. It has previously been shown to bind members of two families of small GTPases, namely Rab 11 from the Rab family and ARF5 from the ADP-Ribosylation Factor (ARF) family. Rabll-FIP4 has also been shown to have a partially overlapping localisation with the Rab 11 recycling endosome. Its function remains undetermined. Here, three aspects of Rabl 1-FIP4 are investigated. Firstly, a binding study confirms that FIP4 binds to Rab 11 and ARF5 and identifies ARF6 and Rab5 as additional binding partners. It also shows that Rab 11-FIP4 can simultaneously bind a Rab and ARF family member. Secondly, the localisation of Rab 11-FIP4 and its colocalisation with its binding partners is examined in interphase cells and also in cells at various stages of cell division. This shows that Rab 11-FIP4 and its binding partners show various degrees of overlap in interphase endosomes and particularly that they all show striking and similar localisations throughout mitosis and cytokinesis. The third part of this study examines the possible functional roles which Rab 11- FIP4, Rab 11 and ARF5 may play in cytokinesis. Although a functional role for Rab 11- FIP4 is not established, it is shown that both Rab 11 and ARF5 play an important role in cytokinesis.