CYP2A13 and lung carcinoma: In the metabolism of xenobiotics by cytochrome P450, nitrosamine 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK) was downregulated in the HFD group, though it was partially upregulated in the MPE group, consistent with the role of CYP2A13 in its activation in lung cancer [45].