PCR analysis of peripheral blood cell DNA. Oligonucleotide primer pairs are specific for (A) the murine wild-type TF allele and (B) the neomycin gene from the TF null allele. Lane 1 in each panel contains molecular weight markers. Results from 2 mice in each group are shown. Wild-type mice given transplants with wild-type marrow are designated as wt BM in wt, wild-type mice given transplants with low-TF marrow as low-TF BM in wt, and low-TF mice given transplants with wild-type marrow as wt BM in low-TF.