Abstract: The present invention relates to an analytical process for the assessment of the genotoxic potential, also termed mutagenic or transforming activity, of an agent in respect to hematopoietic cells. The agent can be selected from natural and synthetic chemical compounds, and preferably from heterologous expression cassettes, e.g. contained in non-natural viral particles or non-natural viral nucleic acid constructs, e.g. nucleic acid constructs containing a viral element.