Both isomeric compounds 29 and 48 might serve as potential leads for the development of new anti-cancer therapeutics due to their inhibitory activity against Dyrk1A and −1B, which we also demonstrated in intact cells; 29 might offer an additional advantage in the case of glioblastoma, due to the simultaneous inhibition of Dyrk1A and Mnk1, which were both validated as new promising targets for this tumor entity [38], [99]. Here, MKNK1 is linked to neoplasm.