HDAC4 and squamous cell carcinoma: The level of expression of different HDACs was comparable between different subtypes, with slight tendency of elevated expression levels in squamous cell carcinoma (Additional file 1).Immunoblotting with total cell lysates from frozen cancer tissue samples (n = 7) showed correlation between the RNA levels and the protein expression levels for representative members (HDAC1 and HDAC4) of class I and class II HDACs (Figure 1C).