Family-wide assignment of DENN specificity. Human DENND3 (A), DENND5A and DENND5B (B), MTMR5 and MTMR13 (C), and MADD (D) were tested against a representative panel of human Rab proteins using the GDP-releasing assay. All assays used 10 nM of FLAG-tagged DENN protein purified from HeLa cells. Errors bars show the standard error of the mean. The red line marks double the median value.