Table 4. IC₅₀ Values (μM) of Triapine and Its Derivatives in Different Cancer Cell Lines after 72 h Drug Treatment^a.

^a***p ≤ 0.001, **p ≤ 0.01, *p ≤ 0.05; ^n.s., not significantly different, calculated by student’s t test with Welch’s correction; n.t., not tested.