Specific uptake of TPP into tumor cells at 37°C.

<p>Human breast cancer cell lines expressing different levels of memHsp70 (MCF7, MDA-MB-231, T47D) were incubated with CF-labeled TPP or a scrambled peptide for 30 min at 37°C and the internalization of peptides imaged using confocal microscopy. <b>A.</b> TPP (green, right panel), but not the scrambled peptide (left panel) is internalized into the tumor cell lines. The appearance of the TPP (green, right panel) in well-defined, localized points suggests that the association of the peptide with intracellular vesicles is related to the memHsp70 expression status. The numbers shown as inserts indicate the percentage of memHsp70 positively stained cells. DAPI staining allows visualization of the nucleus (blue). Objective 2×; scale bar 50 µm. <b>B.</b> Individual cells were imaged as a z-stack in order to better illustrate the intracellular localization of TPP. Images are representative three-frame composites from approximately mid-way in the stack. Immunofluorescence staining, (left panel); brightfield, (right panel). Objective 63×; scale bar 10 µm.