SHMT1 and lung carcinoma: The iSHMT2 treatment strongly downregulates the SHMT2 protein in the single and combined (iSHMT1+2) transfections, as expected, on the other hand, iSHMT1 induces the upregulation of the SHMT2 protein levels, confirming that the expression of SHMT1 and SHMT2 isozymes is somewhat interconnected in the lung cancer cell lines that we have analyzed (A549 and H1299).