SADS occur in MEFs and senescent cells within human tumors. (A) Cycling MEFs (top right) have condensed minor satellite (red), whereas senescent MEFs (bottom left) have distended minor satellite. (B–D) A senescent MEF with coalesced and elongated chromocenters (DAPI) and stringy minor satellite (red). The arrowhead points to a particularly elongated chromocenter (D) associated with a highly decondensed minor satellite (C). (E) Senescent MEFs, as shown in B, stain positive for β-gal. (F–J) Serial sections reveal SADS in PIN tissue. Using H&E staining (F and magnified in G) to identify PIN, which contains senescent cells as indicated by positive β-gal staining (H) and distended satellites by α-sat (green) and sat II (red; I). Signals from I (white box) are enlarged in J. (K and L) Malignant prostate (K) and thyroid (L) tumors, which lack senescent cells, typically have round, compact signals of α-sat (green) and sat II (red).