BI-D1870 is an ATP-competitive inhibitor of S6 ribosome for RSK1/2/3/4 with IC50 of 31 nM/24 nM/18 nM/15 nM in cell-free assays, respectively; 10- to 100-fold selectivity for RSK than MST2, GSK-3β, MARK3, CK1 and Aurora B. BI-D1870 exhibits anticancer attributes including the generation of reactive oxygen species (ROS) and increases in endoplasmic reticulum (ER) stress and autophagy.