TP53 and neoplasm: As efficient GOF action by mutant TP53 requires the accumulation of mutant p53 in the affected cell, the determination of p53 overexpression using immunohistochemistry could suggest the presence of GOF mutations in TP53. In contrast, no detectable p53 in tumour cells indicates the presence of an LOF mutation in TP53. Thus, the different responses of CRCs to adjuvant chemotherapy depend on the expression status of p53.