1. Compound 5 Structure hLDHA IC 50 0.032 ± 0.016 µM hLDHB IC 50 2.512 ± 0.07 µM Supplementary Figure S1

2. Supplementary Figure S2 Compound 2 -9-8-7-6-5 % inhibition 25 50 75 100 5  M 30  M 60  M 120  M B A concentration in cell,  M Cmpd 1Cmpd 2Cmpd 3 NADHCmpd IC50 67 nM 43 nM 22 nM 12 nM

3. 13 C 15 N- Arg/Lys HEK293 SILAC Mix 1:1 Ratio SNU398 12 C 14 N- Arg/Lys Protein Concentration Prepare lysates triplicate Protein Concentration recomb LDHA Spike 13 C 15 N- Arg/Lys HEK293 SILAC Supplementary Figure S3 Trypsin digest LC-MS/MS Trypsin digest LC-MS/MS B A Snu398 HepG2 LDHA copies/cell LDHA cell concentration 4.7 x 10 6 2.9 x 10 6 2.6 1.5 C Hek293 3.8 x 10 6 5.4 MM 973 975 977 Relative Intensity % 0 100 rLDHA HEK293 Relative Intensity % 0 100 973 975 977 HEK293Snu398 LLIVSNPVDILTYVAWK

4. LDHA LDHB A CD Snu398MDA-MB-453MiaPaCa-2NCI-H1395Snu423U251A2780Cal-27HepG2786-O LDHA,  M  -actin Supplementary Figure S4 7=042 LDHA 234 trxn 2, days trxn 1, days WB + + + + + + + LDHAsi 7 E HepG2KidneyMelanomaLiverColonPancreasBreast LDHA  -actin LDHB LDHA,  M B

5. Supplementary Figure S5

6. FBP, nmol/mln cells DMSOCmpd 1Cmpd 2 Supplementary Figure S6 FBP, nmol/mln cells < 0.3 DMSOCmpd 1Cmpd 2 A B

7. Supplementary Figure S7

8. relative pathway activity HepG2Snu398 pentose phosphate glycolysis fatty acid synthesis glutaminolysis Supplementary Figure S8 A B