Additionally, the expressions of MSH6/2 and PD-L1 mRNA were lower in NFPA subtypes with Knosp grade 3–4 than in NFPA subtypes with Knosp grade 1–2, although a significant p value could not be obtained due to the small number of samples in each subtype (Supplementary Materials Figure S2). This evidence concerns the gene MSH6 and non-functioning pituitary adenoma.