For example, dCas9-Dnmt3a-based system has been used to increase DNA methylation for repressing the transcription of oncogenes CDKN2A (cyclin-dependent kinase inhibitor 2A) and BACH2 (BTB domain and CNC homolog 2) in cancer development associated with aberrant DNA methylation [21, 22]. Here, CDKN2A is linked to cancer.