TP53 and colon carcinoma: Berndtsson et al. [69] confirmed the threshold nature of the apoptotic response in p53-WT HCT116 colon carcinoma and 224 melanoma cells exposed to cisplatin for 6 h, with significant levels of apoptosis only being seen after much higher cisplatin concentrations (threshold at approximately 10 μM) than those used in the CF assay, as shown in Figure 3.