Figure 2.

Rb1 Promoter polymorphism between BALB/cHeNhg and CBA/Ca mice. a: Sequence of the Rb1 promoter region between - 267 nt and – 288 nt determined for strains BALB/cHeNhg and CBA/Ca , showing structure of the BALB specific TCGCCC insertion. Base numbering relative to ATG in exon 1. b: Position of the BALB specific hexanucleotide insertion relative to the SP1, ATF and E2F core binding sites according to [32]. c: Association of the Rb1 promoter genotype in BALB/cHeNhg x (BALB/cHeNhg x CBA/Ca) backcrossed mice with osteosarcoma induction. Kaplan-Meier plot of osteosarcoma appearance in 169 BALB/cHeNhg x (BALB/cHeNhg x CBA/Ca) backcrossed mice grouped according to their genotypes at the Rb1 promoter. Mice inheriting the B/C genotype have a significantly shorter latency time and higher overall osteosarcoma incidence than mice with the B/B genotype (p = 0.0007, Log-Rank Test). Of 79 mice inheriting the B/B genotype 14 developed an osteosarcoma, whereas out of 90 mice with the B/C genotype 30 developed an osteosarcoma. Insert: PCR products following amplification of a 122/128 bp fragment (primer 1005f and 1128r) encompassing the site of the BALB/c specific insertion. The insertion specific fragment was used for genotyping all mice of the backcrossed cohort