Signal transduction pathways allow molecules inside of a cell to be altered by molecules on the outside. Some pathways work via cilia on the cell surface. Defects in ciliary formation and function are linked to several human diseases, including cancer. Epifluorescence imaging shows a cluster of human retinal pigment epithelium (RPE) cells displaying primary cilia. Cells were serum starved for 24 hours before imaging to induce cilia formation. Cilia (blue, anti-acetylated tubulin), EHD1 (green, ciliary pocket), centrosome (red, anti-Cep164) and nuclei (dark red).