RP1 is a member of the EB1 family of proteins. The members of the human EB1 family are encoded by 3 genes: MAPRE1, MAPRE2, and MAPRE3. The proteins encoded by these genes are EB1, RP1, and EBF3. These proteins have been shown to associate with the tumor suppressor APC (adenomatous polyposis coli) and p150glued. The cellular function of RP1 has not been fully characterized but it may be involved in microtubule polymerization and spindle function.