TP53 and cancer: Against HCT116 p53–/– cells, cisplatin showed less activity (8.1 ± 1.8 μM) than for HCT116 p53+/+ cells (3.5 ± 1.5 μM) consistent with the increased resistance of cancer cells lacking p53 to many standard chemotherapeutic agents, while some of the flexicates were extremely active (2a annd 2c) with IC50 values in the nanomolar range e.g. ΔFe-[Fe2L2c3]Cl4 (40 ± 3 nM) [Fig. 5(c)].