MYCN and cancer: These PNA analogs of different length were tested in the “miRNA-34a–MYCN” axis (Ruiz-Perez et al., 2017), being the MYCN oncogene a validated target of tumor suppressive miRNA-34a in different cancers (Wei et al., 2008), including Neuroblastoma (Stallings et al., 2010; Zammit et al., 2018).