Prostate apoptosis response protein PAR-4 (2-7) [Homo sapiens] is a peptide with the sequence H2N-Ala-Thr-Gly-Gly-Tyr-Arg-OH, MW= 623.66.

Prostate apoptosis response-4 (Par-4) is a human gene coding for a tumor-suppressor protein that induces apoptosis in cancer cells, but not in normal cells. The tumor suppressor PAR-4 represses and activates transcription. The protein encoded by this gene is a PAR-4-interacting protein that itself functions as a transcriptional repressor. It contains a putative leucine zipper domain that interacts with the zinc finger DNA binding domain of PAR-4. This protein is specifically upregulated during apoptosis of prostate cells [1].

The active domain of the Par-4 protein has been found to confer cancer resistance in transgenic mice without compromising normal viability or aging and may have therapeutic significance [2].