Though Nsp1 transfection in HEK293 cells also increased the S-cMyc/FL-cMyc ratio, its effect on FL-cMyc was limited (Fig. 2C), consistent with limited inhibition of HEK293 cell proliferation by Nsp1 and further suggesting that the antiproliferation effect of Nsp1 is rather specific to cancer cells. Here, SH2D3A is linked to cancer.