Since the proline analog thiazolidine-2-carboxylate (T2C) was recently shown in solution to be a mechanism-based inactivator of a bacterial surrogate for human PRODH (PutA), producing covalent adduction to its internal FAD (Campbell et al. 2020), we were most interested in comparing the inhibitory properties of T2C with N-PPG on human PRODH in isolated mitochondria from the human breast cancer cell line, ZR-75-1. This evidence concerns the gene PRODH and breast carcinoma.