Rab1-GTP is detected by immunocytochemistry using 045189. Method: HeLa cells are grown in standard culture conditions, fixed with paraformaldehyde (3%), permeablized in PBS+BSA 0.2%+Saponin 0.05% and incubated with 045189 (1ug/ml ) in PBS-BSA-Saponin). After incubation for 30 min at RT and several washes in PBS, cells are treated with a goat anti-human (Cy3) antibody in PBS-BSA-Saponin for 30 min at RT, washed and mounted in Moewiol. Nuclei are stained with DAPI. Picture courtesy of Dr. Moutel, Dr. Franck Perez lab, Curie Institute, Paris.