KDR and neoplasm: PCR linkage analysis demonstrated that the Tg(flk1:RFP)is18 chromosome 3 haplotype at marker Z5197 located ∼105 Kb from the integration site segregated with the transgene and tumor phenotype in 100 RFP expressing progeny from a tumor-bearing F5 adult Tg(flk1:RFP)is18 female outcrossed to a WIK wild type male (Table 1).