SHMT1 and lung carcinoma: Mice lacking SHMT1 are vital but have an abnormal accumulation of uracil in DNA.4 To test if iSHMT can induce uracil misincorporation in DNA of A549 and H1299 lung cancer cells, we employed two different techniques, namely the comet assay20 (performed 72 h after the transfection), which measures the formation of comets in cells treated with bacterial uracil DNA glycosidase, and a qPCR method based on the ability of two commercial polymerases to proceed in the elongation when uracil is erroneously incorporated in the template DNA sequence (performed 48 h after the transfection).