RPL21 and head and neck squamous cell carcinoma: The identical proteins encoded by the two RP transcripts RPL21 and Rpl29 have the same 3′ UTR and differ only with respect to their 5′ UTRs, which differ further in individuals with human head and neck squamous cell carcinoma (HNSCC); in fact, Rpl21 and Rpl29 show increased overall translational efficiency in squamous cell carcinoma cells [86,89].