CD274 and classic Hodgkin lymphoma: An increase of PD-1 constitutive expression is described on classical Hodgkin lymphoma (cHL) and mediastinal large B-cell lymphoma cell lines[13], identifying PD-L1 and PD-L2 as key targets at the 9p24.1 amplification region, that includes the Janus kinase 2 (JAK2) locus.