LY2857785 shows good selectivity against a panel of 114 protein kinases, with only 5 other protein kinases inhibited with potency (IC50) less than 0.1 μM, and a total of 14 kinases less than 1 μM. At the cellular level, LY2857785 inhibits CTD P-Ser2 and CTD P-Ser5 in U2OS cells at IC50s 0.089 (n=13) and 0.042 (n=1) μM, respectively. However, LY2857785 only induces a moderate G2-M DNA content increase, from 35% to 55%, with EC50 0.135 μM. LY2857785 shows potent compound exposure- and time-dependent cell proliferation inhibition in MV-4-11, RPMI8226, and L363 cells. When incubated between 4 to 24 hours, the cell growth inhibition potency reaches a maximal effect at 8 hours with IC50s 0.04, 0.2, and 0.5 μM for MV-4-11, RPMI8226, and L363 cells, respectively. LY2857785-induced cancer cell apoptosis is also time dependent, reaching maximal potency at 8 hours with IC50 0.5 μM in L363 cells.