DDX53 and cancer: PTT also promoted CT26 cancer cells to upregulate mouse UL16-binding protein-like transcript 1 (MULT-1), a stress-induced ligand for NKG2D receptor on NK cells39 (Fig. 6b) as well as HSP70, a key ‘danger’ signal involved in recruitment and activation of DCs and lymphocytes40,41 (Fig. 6c).