Two of the Rab family of proteins involved in vesicle trafficking were targeted in a specimen of pig kidney cells. Rab5a was tagged with the green fluorescent protein mEmerald and Rab4a was fluorescently labeled with mCherry. The Rab5a protein is a marker of early endosomes, while Rab4a is a marker of recycling endosomes. In addition to these two endosomal types, cells also contain a third form of endosome known as the late endosome. Markers of late endosomes include Rab7 and Rab9.