In the Pdcd1-overexpressing K562 cancer cells, the basal levels of caspase-3/7 activity and apoptosis (as determined by the luminescence intensity of Annexin V) were considerably higher, even in the absence of DOX; these levels were 240.6% (p < 0.01) and 190.0% (p < 0.01), respectively, of those in the control (mock) cells. Here, PDCD1 is linked to cancer.