tokens: ( 10 ) described how two NB cell lines derived from the same patient can elicit a different p53 status : wt p53 for SK - N - BE ( 1a ) established before treatment , and mutated p53 for SK - N - BE ( 2c ) established after relapse of the patient under treatment with cytotoxic agents such as cyclophosphamide , doxorubicin , vincristine and radiotherapy .