RAC1 and head and neck squamous cell carcinoma: Subsequent clinicopathological analyses of HNSCC cases with RAC1-amp/gain (n = 206) showed that they were significantly associated with TP53 mutation (p = 4.05 × 10−7 ****) and extracapsular spread (p = 0.004 **); both are characteristic features of aggressive HNSCC [21,22] (Supplementary Table S2).