Inhibition of polymerization Enhancement of polymerization Fig. S1 A B IC50 = 26 nM C Inhibition of polymerization (1 mM GTP) Enhancement of polymerization (without GTP) (mM) Vehicle LY2523355 100 Vincristine 0.1 Vincristine 1 Vincristine 3 -0.01 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 10 20 30 40 50 60 Time (min) Absorbance at 340 nm LY2523355 100 Paclitaxel 3 Paclitaxel 10

Fig. S2 A B C DNA Pericentrin Eg5 Merge Control LY2523355

Fig. S2 (cont.) D E Hours after Plating % Confluence 100nM 0nM 1.2nM -4 -3 -2 -1 1 10 20 30 40 3 h 1 h 6 h 12 h 18 h 24 h Concentration (log mM) Apoptotic Index (%) E

Caspase activity (% of control) Fig. S3 DNA pHH3 (S10) pH2AX(S139) Merge LY2523355 Control A B Mad2 + − 24 48 72 Mad2 siRNA β-actin Time (h) C D Untreated Control siRNA Mad2 siRNA LY2523355 Concentration 100 300 500 Caspase activity (% of control) Untreated Control siRNA Mad2 siRNA

Fig. S4 A B a b c

C D

% of cancer cells positive for pHH3 Fig. S5 DNA TUNEL pHH3 Merge A Control LY2523355 5 10 15 20 25 30 35 40 1 2 3 4 Treatment Groups % of cancer cells positive for pHH3 B