Expression of NRASV12 in bone marrow of line 6468 mice by RT-PCR. Total bone marrow was harvested from singly and doubly transgenic littermates, as indicated, and total RNA was extracted. RNA was DNase treated, and NRAS RT-PCR was performed with (+RT) and without (-RT) reverse transcriptase. Glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) RT-PCR was performed on the same samples to verify integrity and loading.