CBX2 directly targets the p21 gene in a BMI1-independent manner. (A) Schematic representation of the CDKN1A gene with locations of primers as indicated. (B) CBX2 ChIP analyses of prestimulated CB CD34⁺ cells on p21 gene and p14^ARF promoter. (C) BMI1 ChIP on the p21 gene locus and the p14^ARF promoter. (D) H3K27Me3 ChIP experiments showing enrichment across the p21 gene and the p14^ARF promoter. (E) H2AK119ub ChIP analyses on the p21 and p14^ARF loci. ChIP experiments are depicted as percentage of input and the data represent the average of 3 independent experiments on different CB batches. Statistical analysis was performed using Student t test. Mean ± standard deviation (*P < .05, **P < .005). IgG, immunoglobulin G.