TDP1 and cancer: Both these assays are based on anchorage-dependent cell growth, which leads us to the following thought: “Can poisoning of TDP1 via dysregulation of TDP1-activity using either hTdp1H493N or hTdp1H263A mutants also decrease the anchorage-independent colony formation, which is suggested to be a surrogate for the ability to form cancer metastasis [33, 34]?” Indeed, hTdp1H263A significantly reduced colony formation by ∼30% (unpaired student t-test; p=0.0074), while hTdp1H493N showed a significant reduction of ∼45% (p=0.0001), compared to vector control (Figure 8).