PSMA8 is a subunit of the 20S proteasome, and hypermethylation and transcriptional downregulation of PSMA8 in BOS patient samples (Figure 4, C and D) suggests downregulation of the 26S proteasome–mediated degradation of β-catenin in BOS patient tissues (70). This evidence concerns the gene PSMA8 and Buschke-Ollendorff syndrome.