We subsequently examined the expression patterns of liver specific aromatase promoter exon 1s (1b, I.5, and I.6), which plays very important roles in regulation of aromatase mRNA expression [16, 17], in HepG2 with or without the coculture with carcinoma cell lines by exon 1-specific RT-PCR analyses in order to further evaluate the regulation of intrahepatic aromatase. This evidence concerns the gene CYP19A1 and carcinoma.