Figure 1

(a) An ALT-positive case. The arrow indicates ALT-associated promyelocytic leukemia protein bodies (APBs) in a tumor cell. (b) An ALT-negative case, which shows telomere shortening. For comparison, the arrowheads indicate non-tumor stromal cells that show robust telomeres, as would be expected in normal tissue. The background cellular DNA is stained blue by DAPI, telomere DNA is stained red by telomere probe, and centromeres are stained green by centromere probe. Original magnification × 400.