Through screening of an expression library, a cDNA sequence has been identified that encodes a protein that interacts with human CD33, the DNA being highly homologous to a portion of the human dystrophin gene. A region of that cDNA has been identified as an important regulatory element in controlling expression, both transcription and translation, of the DNA with which it is associated. This DNA sequence element may be used as a regulatory cassette in conjunction with any suitable gene, to modify gene expression. The putative controlling DNA sequence element contains a minimum of 137 base pairs (FIG. 1) to 147 base pairs (FIG. 1A) and a maximum of 287 base pairs (FIG. 1B).