Details:
The assembly of chromatin into senescence-associated heterochromatin foci (SAHF), transcriptionally-silent heterochromatin structures present in senescent cells, containing the condensed chromatin of one chromosome, and enriched for histone modifications. Formation of these chromatin structures is thought to repress expression of proliferation-promoting genes. [GOC:yaf, PMID:15621527, PMID:21248468]