HOXB6 and neoplasm of mediastinum: HN-PG and the suspected non-chromaffin mediastinal tumours had low expression of the chromaffin cell marker CARTPT24, 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 (Fig. 2H, Supplementary Fig. 6).