In contrast, stable expression of Onc-p53 mutants p53-R175H, p53-R273H or p53-R281G in H1299 (p53-null) lung cancer cells shortened track length of replicating DNA fibers compared to that observed in H1299 cells transfected with empty vector or stably expressing a deletion mutant (p53 del100–300), which lacks the mutated p53 allele (Fig. S1G,H). The gene discussed is TP53; the disease is lung cancer.