Sarkar et al. Figure 1


Northern blot analysis of total RNA extracted from mammary tumors and normal mammary glands of mice. RNA was prepared from frozen tissue following the LiCl-urea method, and aliquots of 25 g RNA were denatured, size-fractionated on 0.8% agarose gels, capillary transferred to filters and hybridized with a 32P-labeled MMTVrep probe that represented the entire MMTV genome (Panel A). The filter was autoradiographed for a desired length of time in the presence of an intensifying screen at -70 ° C. Subsequently, the filter was sequentially stripped off and rehybridized with jun C (Panel B) and actin (Panel C) probes, respectively. The 8.6 kb and 3.8 kb transcripts shown in Panel A represent the genome size and subgenomic (envelope gene) transcripts of MMTV. Note that both mammary tumors and normal tissue express the two known 3.1 and 2.7 kb transcripts of c-jun (Panel B). Because of incomplete stripping (intentional) of the MMTVrep probe, the autoradiograph also shows the MMTV transcripts. Panel A: lane 1, RIII/Sa, mouse tumor; lane 2, BALB/cfC3H mouse tumor; lane 3, lactating mammary gland from a 6 month old RIII/Sa mouse; lane 4, mammary gland from a 4 month old virgin RIII/Sa mouse.