Immunofluorescence analysis (IFA) was as described (43 (link)). Antibodies for IFA were used at the following dilutions: mouse anti-HA-epitope IgG (Santa Cruz Biotechnology Inc.) at 1:1000, rabbit anti-Rab11 at 1:200 (54 (link)), rabbit anti-Rab5a at 1:200 (55 (link)), mouse anti-p67 at 1:1000 (56 (link)), mouse anti-BiP at 1:10 000 (57 (link)), rabbit anti-VSG221 at 1:1000 (55 (link)), rabbit anti-RabX2 at 1:50 (58 (link)), rabbit anti-IGP48 (this study) at 1:50. Secondary antibodies were used at the following dilutions: anti-mouse Oregon Green (Molecular Probes) at 1:1000 and anti-rabbit Cy3 (Sigma) at 1:1000. Cells were examined on a Nikon Eclipse E600 epifluorescence microscope fitted with optically matched filter blocks and a Hamamatsu ORCA charge-coupled-device camera. Digital images were captured using Metamorph software (Universal Imaging Corp.) on a computer running the Windows XP operating system (Microsoft Inc.) and the raw images processed using Photoshop CS6 software (Adobe Systems Inc.). Confocal z-sections were acquired using a Leica DMIRE2 microscope and deconvolved using Huygens Professional software.