FOXD1 and oral cavity squamous cell carcinoma: Although the mRNA levels of FOXD1 showed no differences between the groups of age (<0 vs. ≥60), gender (female vs. male) and pathologic staging (T1/2 vs. T3/4; N0 vs. N1; stage I/II vs. II/IV), FOXD1 expression was relatively higher in primary tumors derived from head and neck cancer patients without smoking history or oral squamous cell carcinoma (OSCC) subdivision (Figure 2C).