Humans lack the enzymes required for generating polyunsaturated FAs from saturated and mono-unsaturated species; however, SCD1, which introduces a double bond in the Δ9 position of saturated fatty acids (SFAs) to produce mono-unsaturated fatty acids (MUFAs), has an increased expression in various cancer cells and is involved in the promotion of cancer cell proliferation, migration, metastasis, and tumor growth (37, 38). The gene discussed is SCD; the disease is cancer.