PTGS2 and cancer: Fluorocoxib Q enables targeted visualization of COX-2 and ROS inpathological tissues.13 Fluorocoxib Q exhibitsextremely low fluorescence emission due to the quenching of the excitedelectronic state of the carboxy-X-rhodamine by the nitroxide radicalwithin the molecule.13 Upon radical trappingin cancer cells by reactive oxygen species (ROS), the COX-2-targetedfluorocoxib Q probe becomes fluorescently activated, making it effectivefor tumor imaging.