In order to understand the degree of selectivity these complexes have for Cys or Sec residues in the human cell, Meier‐Menches and coworkers used advanced chemoproteomic approaches to investigate the binding of a Au(III)C^N cyclometalated complex, [Au(CNOxN)Cl2] (CNOxN = 2‐(phenyl‐(2‐pyridinylmethylene)aminoxy acetic acid, Figure 3B), with the CysSec‐dyad of thioredoxin reductase 1 (TXNRD1) in human SW480 colon cancer cells.[46] In this work, the Au(III) organometallic complex exhibited selectivity to target TXNRD1, as well as potent inhibition against the isolated enzyme and cell extracts. The gene discussed is TXNRD1; the disease is malignant colon neoplasm.