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. Here, CLK3 is linked to cancer.