Expression of CAT constructs carrying progressive 5′ deletion mutants of the flanking region of the WASP gene. (A) Comparison of the expression of W-CAT5′▵-1,580, W-CAT5′▵-1,167, W-CAT5′▵-988, W-CAT5′▵-829, W-CAT5′▵-365, and W-CAT5′▵-137 in Jurkat cells. (B) Analysis of W-CAT5′▵-137 in Jurkat, HEL, and Dami cells. HeLa cells were used as a negative control.