RPS18 and head and neck squamous cell carcinoma: Interestingly, the four best normalization genes in both groups given by geNorm as well as NormFinder were ALAS, GAPDH, RPS18 and SHAD. Similarly, the four worst genes were ACT, KALPHA, RPL27 and RPS29. In the HNSCC group, the best combination of two genes was GAPDH and SHAD with an M value of 0.732.