Short telomeres block tumor formation in a p53 dependent manner. A) Intergenerational breeding scheme. Vertical bars represent telomere lengths. B) Kaplan-Meier survival analysis of Myc iG7 mTR +/- p53 +/+ (black dashed, n=11) Myc iG7 mTR -/- p53 +/+ (red dashed, n=20), Myc iG7 mTR +/- p53 +/-(black solid, n=7), and Myc iG7 mTR -/- p53 +/- (red, solid n=9) cohorts. Myc p53+/- animals invariably develop Myc p53-/- tumors at around 40 days. Short telomeres promote chromosomal abnormalities in p53 deficient lymphomas. C) Q-FISH analysis of metaphase spreads from Myc mTR +/- p53 -/- (top) and Myc mTR -/-p53 -/- (bottom) lymphomas. Ten metaphases each from three separate lymphomas are represented for each genotype. D) Quantitation of chromosome abnormalities. The number of chromosome end-to-end fusions (red bars) and non-reciprocal translocations (blue bars) per metaphase are shown. (10 metaphases per tumor n=3). Bars indicate standard error.