The cells may have one or more efflux pumps (such as P-gp and MRP) that can pump the dye out. The function of these pumps can be blocked by treatments that de-energize the cells. Additionally, dye that is simply bound to the surface may be washed off.
May be your dye has not been internalized in to the cell and retaining in the surface as an aggregate. Probably you may need to double check your staining protocol and provide sufficient time for the internalization. I would highly recommend you to try the same dye/method in a different cell line as a control. Hope this help!
The fluorescent tagging of proteins in the natural environment of the cell is an emerging technique in cell biology. In this issue of Chemistry & Biology, Gautier et al. introduce a fluorescent labeling procedure orthogonal to existing ones, enabling tagging of two different proteins in living cells.
Despite the number of university students who take courses in multiple science disciplines, little is known about how they connect concepts between disciplines. Energy is a concept that underlies all scientific phenomena and, as such, provides an appropriate context in which to investigate student connections and misconnections across disciplines....