Nkx2.5 has also been observed to be highly expressed in squamous cell carcinoma of skin (28), T-cell acute lymphoblastic leukemia (30), ovarian yolk sac tumor (29), and papillary thyroid carcinoma (27), while lowly expressed in basal cell carcinoma of skin (28). This evidence concerns the gene NKX2-5 and skin squamous cell carcinoma.