RB1 and neoplasm: To better assess the effect of the three adenovirus mutants in vitro, the dosages of GCV were optimized and the time point of the treatment in a panel of tumour cell lines varying in Rb status; metastatic potential and tissue of origin, including MKN45 (gastric carcinoma cell line with a high frequency of metastasis and wild type Rb); A549 (lung carcinoma cell line with mutant Rb); HepG2 (hepatic carcinoma cell line with mutant Rb) and A2780 (ovarian cancer cell line with mutant Rb) assayed.