tokens: To determine which sequences in the rat P450c17 promoter may be responsible for basal and cAMP - stimulated gene transcription , deletion constructs containing between - 1 , 560 and - 53 base pairs of 5 ' - flanking DNA from the rat P450c17 gene were ligated to plasmids expressing the reporter gene luciferase and transfected into two mouse cell lines , adrenal Y - 1 cells , and testicular Leydig MA - 10 cells .