RAC1 and head and neck squamous cell carcinoma: Furthermore, in head and neck squamous cell carcinoma (HNSCC) cells, ESRP1 knockdown enhanced cell motility by affecting the dynamics of the actin cytoskeleton through the induction of Rac1b isoform via regulation of Rac1 isoform splicing, indicating that ESRP1 suppresses cell migration of HNSCC cells [51].