CDKN1A and hereditary elliptocytosis: Furthermore, the observed G0/G1 cell cycle arrest, particularly in HE-treated cells, could potentially involve modulation of key regulators such as p21^Cip1/Waf1^ and p27^Kip1^, which inhibit cyclin D-CDK4/6 complexes and thereby halt progression from G1 to S phase [55].