GlaxoSmithKline (GSK) has found that both the PRMT1 inhibitor GSK3368712 (GSK712) and the PRMT5 inhibitor GSK3326593 (GSK593) have anti-tumor effects in a variety of cancer cell lines, with the exception of HNSCC (64). Here, PRMT5 is linked to head and neck squamous cell carcinoma.