Fig. 2. Trafficking pathways in polarized epithelial cells. From the TGN, cargo can be transported directly to the apical or basolateral membrane (red). Basolateral cargo can also reach the plasma membrane through endosomes (blue). Following initial transport to the basolateral membrane, apical cargo can be sorted to the apical membrane via the transcytotic route (green). The arrows marked with a gold outline together constitute the basolateral recycling pathway. The apical recycling pathway and the apical-to-basolateral transcytotic pathway are omitted for clarity. EE, early endosomes; ER, endoplasmic reticulum; LE, late endosomes; RE, recycling endosomes; TGN, trans-Golgi network.