CLK1 and cancer: MU1210 is a potent inhibitor of CLKs with IC50 values of 8 nM for CLK1, 20 nM for CLK2, 12 nM for CLK4, and more than 3000 nM for CLK3; notably, off target against HIPKs and DYRKs were observed at relatively high IC50 concentration.134 MU1210 attenuated MCF-7 cell proliferation and showed IC50 of 4.6 μM in cell viability.134 However, the detailed biological functions and potential of MU1210 in cancer treatment are largely uncharacterized.