A reduction of the levels of PPP1CA mimicked the cancer stem-like cell phenotype of Spn downregulation, suggesting that the mechanism of Spn involves PP1a.
Both PP1alpha-mediated G(1) arrest and PP1alpha phosphorylation in late G(1) require the presence of pRb, indicating that PP1alpha is a crucial regulator of the pRb pathway, which is almost invariably mutated in human cancer.
PPP1A, which has been postulated as a MEN-1 candidate tumor suppressor gene, and GST3, a gene transcriptionally active in many human cancers, both map distal to the bcl-1 translocation cluster and the region containing MEN-1, and therefore are unlikely to be directly involved in bcl-1 or MEN-1.