To functionally validate the toxic effect of CDKN1A overexpression, we selected cancer cell lines from two tumor types (lung and breast): one with normal copy number and average mRNA expression (“non-compensated”) and one with lower mRNA/protein expression levels than expected by its amplification (“compensated”) (Fig. 4d and Supplementary Fig. S5a). The gene discussed is CDKN1A; the disease is cancer.