Endosomal distribution of Lrrn1. Immunocytochemical analysis of the endosomal uptake of FLAG-Lrrn1 in HeLa cells. (a, d, g, j) Plasma membrane surface-exposed FLAG-Lrrn1 protein detected with an anti-FLAG antibody. (b, c) Colocalisation with total cellular pool of Lrrn1 detected with the GST-IC antiserum. (e, f) Colocalisation with EEA1 (arrowheads in inset in (f)) shows that a significant pool of Lrrn1 cycles through the early endosomes. (h, i) Little overlap with transferrin receptor immunostaining suggests that Lrrn1 does not partition within recycling endosomes. (k-m) A very small proportion of endosomes were found to co-label with FLAG-Lrrn1/EGF ((m), arrowhead in inset). Scale bars = 200 μm except inset in (f) = 50μm.