LRRTM1 is an imprinted gene that shows parent-of-origin association with human handedness and schizophrenia. The left-hand panels (green) show localization of LRRTM1 within MRC-5 SV2 cells, following transfection with untagged (top) or myc+ His-tagged (bottom) LRRTM1, and detection with an LRRTM1 antipeptide. The red panels (middle) show the localization of BAP31, an ER marker. In the right-hand panels, the images for LRRTM1 and BAP31 are overlaid, and the yellow areas indicate the colocalization of the two proteins. LRRTM1 was also detected in the axons and growth cones of neurons but not at the cell surface membrane. Together, these data suggest that LRRTM1 may be involved in intracellular trafficking within axons. For more information on this topic, see the paper by Francks et al. on pages 1129–1139.