PHOX2B and neuroblastoma: In 4 patients with clinically-proven metastatic disease in their bone marrow aspirates (NB4, NB17, NB19, NB25), DTCs stained positive for neuroblastoma immunohistochemical markers PHOX2B and TH, and DTC-enriched fractions from BMAs also expressed elevated levels of PHOX2B and TH on RT-qPCR (Figure 3A).