Guanine nucleotide exchange factor (GEF) for RAB14. Also has some, lesser GEF activity towards RAB35. Belongs to the DENND6 family. Identified as having similarity to the core DENN family and referred to as DENN6B (PubMed:21330364). Prediction methods do not indicate a DENN domain for this sequence and, the exact role of the DENN or this DENN-like domain in GEF activity needs to be clarified.