HNF4A and oral lichen planus: Among the OLP patients, from the enriched signaling pathways we identified several genes coding for proteins involved in nicotine degradation (p = 0.003), cysteine biosynthesis and homocysteine degradation (p = 0.015), as well pathways associated with increased activation of hepatocyte nuclear factor alpha (HNF4A) (p = 0.015) and the modulation of its various downstream signaling molecules (Figure 2B).