RARA and head and neck squamous cell carcinoma: In a head and neck squamous cell carcinoma (HNSCC) cell line xenograft model at a dose of 10 mg/kg/day, an RAR pan-agonist Het called SHet50 [3b] had greater growth inhibition activity in comparison to an RXR-specific Het called OHet72 [3c] and RA [1] (Zacheis et al., 1999).