PRDM5 and squamous cell lung carcinoma: In addition, PRDM5 expression at both mRNA and protein levels has been found to be down‐regulated in lung squamous cell carcinoma due to aberrant cytosine methylation of the promoter of PRDM5 gene, and treatment with a DNA methyltransferase inhibitor reactivates PRDM5 expression accompanied by the decreased proliferation of lung squamous cell carcinoma cells 19.