RAB-dependent trafficking of MT1-MMP in macrophages. Exocytic pathways (green arrows) for newly synthesized MT1-MMP are regulated by RAB8a and can proceed through exocytic vesicles or recycling endosomes. MT1-MMP is endocytosed from the cell surface by a RAB5a-dependent pathway (red arrow). Recycling back to the cell surface, including podosomes, can proceed by fast (orange arrows) and slow (gray arrows) recycling pathways, regulated by RAB14 and RAB22a, respectively. RAB8a, RAB14 and RAB22a thus drive surface exposure of MT1-MMP and subsequent matrix degradation, whereas RAB5a controls recovery of MT1-MMP. Model modified from.25