Transgenic mice express green fluorescent protein (GFP) in juxtaglomerular (JG) cells of the kidney and in granular convoluted tubular cells of the submandibular gland (SMG). Treatment of mice with the ACE inhibitor captopril induces GFP expression in renal vascular smooth muscle cells. In the SMG, GFP expression is androgen responsive. GFP expression is first detected at embryonic day E13 in the adrenal gland and Wolffian duct, by E14 is also seen in the developing renal vasculature, and remains detectable through birth. In adults, renal GFP expression becomes restricted to JG cells. Fetal adrenal and gonadal arteries also express GFP. In the placenta, GFP is observed in giant cell trophoblasts.