Protein-tyrosine phosphatase SHP-1 is the key neg. regulator of numerous signaling pathways. SHP-1 is expressed in the hematopietic and epithelial cells as two structurally similar mRNA transcripts controlled by two different promoters designated P2 and P1, resp. Whereas the transcriptional regulation of the SHP-1 gene P1 promoter has been partially elucidated, the structure and functional control of the P2 promoter remain unknown despite the crit. role played by SHP-1 in the normal and malignant lymphoid and other hematopoetic cells. Using luciferase reporter assays with the set of constructs that contained a gradually truncated intron 1 of the SHP-1 gene, we identified the minimal (