Nf1 analysis. (A) Southern blot of BamHI-digested DNA from leukemic spleens hybridized to an Nf1 probe; 2 germline bands are seen as the probe contains a BamH1 site. Mouse identification numbers are indicated; C indicates germline control tissue; size standards are given in kilobases. *Germline bands. Note loss of the germline allele in mice 17 and 23. (B) Protein lysates from leukemic spleens with a known Nf1 CIS were compared with spleens from clinically healthy CALM-AF10 and WT mice. The Nf1 protein is indicated with ; sizes are in kDa. The blot was reprobed with anti–α-tubulin as a loading control. Intensity of the Nf1 and α-tubulin signals were quantified with ImageJ software, and the ratio compared with that of the WT mouse.