Mutations of Nras and Kras 1 in ENU-induced lymphomas. Mutations of Nras and Kras1 were identified in T-cell lymphomas in Egr1^+/− and Egr1^−/− mice. (A) SSCP analysis revealed a transversion mutation at the first base of codon 61 (CAA > AAA) of Nras in a lymphoma sample from an Egr1^+/− mouse. (B) SSCP revealed a transition mutation at the second base of codon 12 (GGT > GAT) of Kras1 in a lymphoma sample from an Egr1^−/− mouse. The DNA trace of Kras1 is the sequence from the reverse strand.