CD1A and neoplasm: Comparison of the primary ALK+ and ALK− ALCL methylomes with multipotent ETP (CD34+/CD1a−), T cell committed progenitors (CD34+/CD1a+), pre-TCR T cells, TCR-expressing T (CD4+/CD8+ double positive [DP]) cells, and single positive (SP) CD4+ or CD8+ cells revealed that the DNA methylation pattern of ALK+ tumor cells resembled that of ETP (CD34+/CD1a−), whereas the ALK− methylome more closely resembled pre-TCR and DP TCR-expressing T cells (Figure 2A).