HOXB6 and neoplasm of mediastinum: HN-PG and the suspected non-chromaffin mediastinal tumours had low expression of the chromaffin cell marker CARTP24, neural transcriptional regulators (TFAP2B, TOX3, GATA3, POU4F, NEUROG2, PAX2), HOX genes (HOXA1–10, HOXB4, HOXB6–9, HOXC4-HOXC13), and the long non-coding RNA HOTAIR (Figure 2H, Supplementary Figure 5).