PDK4 and cancer: Of note, either suppression of PDK4 activity by PDK4-IN or knockdown of PDK4 via small hairpin RNAs (shRNAs) remarkably deprived cancer cells of these gain-of-functions conferred by PDK4+-stromal cell CM, substantiating the key role of PDK4 in governing the potential of PDK4+-stromal cell CM to modify cancer cell behaviors (Extended Data Fig. 5c–g).