We treated MCF7 human breast adenocarcinoma cells with Doxo (20 and 50 nM) and observed flattened cell morphology (Figure 1—figure supplement 1C), an increase in the nuclear accumulation of cell cycle inhibitor p21 (Figure 1—figure supplement 1D), an increase in the size of nuclei (Figure 1—figure supplement 1E), and an increase in the levels of senescence-associated β-galactosidase activity (SA β-gal) (Figure 1—figure supplement 1F). The gene discussed is CDKN1A; the disease is breast adenocarcinoma.