Senescent cells that have engulfed a cell have a survival advantage. (A–D) H2B-GFP–expressing senescent 4226 (A and B) or MCF-7 (C and D) cells were co-plated with NT H2B-mCherry–expressing 4226 and MCF-7 cells, respectively. 7 d after coplating, cells were trypsinized and sorted one cell per well of a 96-well plate. Each cell was confirmed microscopically and marked as double positive (engulfed, black line) or GFP positive only (not engulfed, red line) and followed over time. (A) Four individual experiments were sorted; a total of n = 23 double-positive and n = 30 GFP-only 4226 cells were followed. Significance was determined by log-rank Mantel–Cox test, *, P < 0.05. (C) One experiment was sorted; a total of n = 47 double-positive and n = 50 GFP-only cells were followed. Experiment terminated at 12 d. Significance was determined by log-rank Mantel–Cox test, *, P < 0.05. Examples of GFP⁺-only cells that died are shown in upper panels of B and D; examples of surviving GFP-expressing cells with an mCherry vesicle within them (red arrowhead) are shown in lower panels of B and D. Scale bars represent 50 µm.