TTK and breast cancer: TTK and CLK2 activities were potently suppressed of the seven identified kinases with IC50 values of 5 nM and 6 nM, respectively.146 Other kinases, such as CLK1 or DYRKs, were also inhibited by CC-671 with different IC50 values.146 Interestingly, results from a series of ActivX KiNativeTM profiling assays indicated that CLK2 was inhibited in vitro by CC-671 with an IC50 of 15 nM; however, TTK was not inhibited.146 Furthermore, treatment of different breast cancer cell lines with CC-671 showed that luminal BC cells were more sensitive to CC-671 treatment versus TNBC cells.146