Information EN4 EN4, a covalent ligand that targets cysteine 171 (C171) of MYC , is selective for c-MYC over N-MYC and L-MYC. EN4 inhibits MYC transcriptional activity, downregulates MYC targets, and impairs tumorigenesis. Targets MYC In vitro EN4 directly targets MYC in cells, reduces MYC and MAX thermal stability, inhibits MYC transcriptional activity, downregulates multiple MYC transcriptional targets, and impairs tumorigenesis. EN4 treatment significantly impairs 231MFP breast cancer cell proliferation in a dose- and time-dependent manner. EN4 impairs the cell survival of MYC transformed mammary epithelial MCF10A cells, but not parental MCF10A cells that are not dependent on MYC. In vivo EN4 treatment initiated after establishment of a 231MFP breast tumor xenograft in immune-deficient mice also significantly attenuates tumor growth in vivo. Cell Research(from reference) Cell lines：231MFP, MDA-MB-231, HEK293T and MCF10A cells Concentrations：50 μM Incubation Time：24 h