Northern analysis of PTPROt and PTPRO transcripts in cell lines and multiple human organs and cell types. (A) Northern analysis of epithelial and lymphoid cell lines. Total RNA (20 μg) from the EBV-transformed lymphoblastoid line, Laz 388, and the small cell lung cancer cell line, NCIH345, was blotted and hybridized with a unique PTPROt 5′ UTR probe (left panel) or a probe derived from the conserved catalytic domain (right panel). The unique PTPROt 5′ UTR probe recognizes only the lymphoid transcript, whereas the common catalytic domain probe identifies both isoforms. (B) Northern analysis of RNAs from multiple human organs and cell types. Blots were hybridized with a unique PTPROt 5′ UTR probe (top panel) or a probe derived from the conserved catalytic domain (middle panel). The major ≈3-kb and ≈4.1-kb minor PTPROt transcripts hybridized with both the PTPROt-specific 5′ probe (top panel) and the common catalytic domain probe (middle panel). The larger (≈5.4 kb) epithelial PTPRO transcripts in brain and kidney only hybridized with the common catalytic domain probe (middle panel). The filters were also hybridized with B-actin (bottom panel) to confirm equal loading.