Cell-type specific activity of sigN gene promoters. A. AX-4 cells were transfected with a reporter vector driving lacZ expression under the control of the Group 1 sigN2 promoter. β-galactosidase activity, detected by X-gal staining, is shown in structures at mound (A), finger (B), slug (C) and early culminant (D) structures (Bar, 0,1 mm). B. A reporter vector where lacZ was placed under the transcriptional control of the Group 2 sigN9 promoter was transfected in AX-4 cells. X-gal staining is shown for mound (E), finger (F), slug (G), early-culminant (H) and culminant (I) structures (Bar, 0,1 mm).