Interestingly, their lifespans would probably be affected very little.

> GzmK does not affect steady-state immune aging or aged immune responses after challenge

Virtually all old mice die of cancer, especially in the lab. If GzmK doesn't mitigate immune system aging, GzmK-null mice are still going to die of cancer, for little or no change in lifespan. (But presumably an improved healthspan due to reduced soft tissue and bone aging.)

> Virtually all old mice die of cancer, especially in the lab. If GzmK doesn't mitigate immune system aging, GzmK-null mice are still going to die of cancer, for little or no change in lifespan.

Would introducing the cancer-reducing TP53 genes found in elephants[1][2] to mice help with this? Or would they likely just be too incompatible, with the species difference being too large?

[1] https://news.cancerresearchuk.org/2023/08/12/can-elephants-g...

[2] https://jamanetwork.com/journals/jama/fullarticle/2456041

> Virtually all old mice die of cancer, especially in the lab

Bret Weinstein did research on this topic which suggested that this is caused by lab mice having extraordinarily long telomeres which cause them to be good at cell repair but bad at limiting neoplasm growth due to delayed apoptosis. The result of this combination would be that lab tests on potential damage done by preparations on these mice is less valid 'cause they are better at repairing such damage than the average mammal due to those long telomeres. It also means nearly all these mice succumb to cancer. They're not normal mice, at all.

The reserve-capacity hypothesis: evolutionary origins and modern implications of the trade-off between tumor-suppression and tissue-repair

Bret S Weinstein 1 , Deborah Ciszek

https://pubmed.ncbi.nlm.nih.gov/11909679/

> Virtually all old mice die of cancer, especially in the lab

Is this related to them being cloned? Did anyone try to get some random mice or is that too taboo?