Northern analysis of DP3 fragments. Subcloned DP3 fragments were used as probes against Northern blots of EML and EPRO RNA samples to confirm differential expression. Approximately 1 μg of mRNA was used for Northern analysis, and the blot was sequentially hybridized to DP3 fragments (1-1, 4-1, and 6-2 in this case). The blot was then hybridized with β-actin to confirm equal loading. The approximate size of each transcript is as follows: 1-1, a doublet of 1.3 and 1.6 kb; 4-1, 3.5 kb; 6-2, 2.5 kb.