RT-PCR was performed to analyse expression patterns of randomly chosen CLCA4, FN1, POSTN, KRT24 and PRR4 in primary HNSCC vs. their corresponding normal tissue mucosa (PTvs.N, Fig. S1A) and ARPGAP25, FAIM3, RASGRP2, LYPD3, SERPINB4 and TP73L in lymph node metastasis vs. their corresponding primary HNSCC (Mvs.PT, Fig. S1B). The gene discussed is CLCA4; the disease is head and neck squamous cell carcinoma.