PtK1 cells were labeled for double immunofluorescence microscopy with the H1 monoclonal antibody to Kinesin-1 (formerly kinesin heavy chain or KHC) and a polyclonal antibody to tubulin. Kinesin-1 and microtubules are shown in the rhodamine (red) and fluorescein (green) channels, respectively. The H1 antibody recognizes a subset of the total cellular Kinesin-1 and stains a post-ER, pre-Golgi system of membranes known as the intermediate compartment. Kinesin-1 is thought to be the motor for moving these membranes from the Golgi to the ER. See related paper by Lippincott-Schwartz, J, Cole, NB, Marotta, A, Conrad, PA & Bloom, GS 1995 J. Cell Biol. 128, 293-306. Contributed by George S. Bloom.