Survey of hematopoietic cell lines for retroviral insertions in Sox4 and expression of Sox4 mRNA. (A) Southern blot analysis of the NFS-58, DA-1, NFS-60, and EML cell lines. XbaI-digested DNA was separated by agarose gel electrophoresis, transferred to nylon membrane, and probed with the 3′ UTR Sox4 fragment shown in Figure 1. XbaI digest of wild-type alleles of murine Sox4 is predicted to yield a 20-kb band. The arrows indicate provirus-induced polymorphisms that are only seen in the NFS-60 DNA. (B) Northern blot analysis of logarithmically growing NFS-58, NFS-60, DA-1, 32Dcl3, and EML cell lines. Total RNA (10 μg) from each cell line was separated by formaldehyde agarose gel electrophoresis, transferred to nylon membrane, and sequentially probed with the 3′ UTR Sox4 fragment (Figure 1) and a murine β-actin fragment. Size markers are indicated on the right. (C) Assessment of Evi1 mRNA expression in EML cells (top row) by Northern blot analysis using a radiolabeled probe for Evi1. EML cells are transfected with either vector or with Evi1 expression plasmid as indicated. The same blot was hybridized for β-actin (bottom row).