Growth curve of Hep-2 cell line. Hep-2 cells were cultured in complete medium, treated with self-conditioned medium (HCM) or with conditioned medium from fibroblast cultures (FCM) and collected 1, 3, 5 and 7 days after medium replacement. Data are means ± s.d. of two independent experiments in duplicates. *P < 0.05. Error bars indicate S.D.