However, particularly in comparison to other colorectal cancer cell lines, Caco-2 exhibit peculiar features, among which: their poorly aggressive tumor phenotype allow studying mechanisms at play at an early stage of cancer progression, also using radiation as a probe to gain molecular understanding; their p53null status (8), given the well-recognized role of this gene in altering the responses to cancer therapeutic agents (9), offers the chance to focus on p53-independent pathways that might also play an important role in the treatment response. The gene discussed is TP53; the disease is cancer.