The notable decrease in expression of the FOS and JUN genes, observed in both the malignant samples group (PTC and FTC) (group 2) and the FTC samples group (group 5), when compared to the group of normal and benign samples (group 1), as well as with the reduced expression of these genes detected in the FTC sample group compared to the PTC samples (group 4), in both PCR array and RT-qPCR analyses, supports the hypothesis that both genes emerge as potential diagnostic molecular markers in thyroid cancer, particularly in FTC. The gene discussed is JUN; the disease is thyroid cancer.