Cell cycling and EF5 binding in SQ20B TF spheroids.

<p>Cycling Ki67 positive cells were peripherally localized (central panel), in contrast to the inverse location of EF5 binding cells (right panel). Hoechst 33342 staining of all cell nuclei shown in the left panel. For the larger, more necrotic TF spheroids (small portion seen in upper left of each panel), the EF5 positive cells lined the inside of the viable rim, since EF5 is only metabolized by viable cells (scale bar 250 μm). Ki67 positive cells were also found peripherally in U87 spheroids of all types, but no EF5 binding was observed (data not shown).