Cytotoxicity and synergism of lithocholic acid and temozolomide in BRCA2-deficient cells. (A) Clonogenic survival of VC-8 (CHO BRCA2-deficient) and VC-8+BRCA2 cells in response to increasing doses of LCA and TMZ, individually. (B) Clonogenic survival of EUFA423 (human BRCA2-deficient) and EUFA423+BRCA2 cells in response to LCA and TMZ, individually. (C) Synergism of LCA and TMZ in VC-8 and VC-8+BRCA2 cells. Analysis using the Chou-Talalay model yielded CI values of 0.43 and 0.79, respectively, mathematically proving synergism. (D) Synergism of LCA and TMZ in EUFA423 and EUFA423+BRCA2 cells. Analysis using the Chou-Talalay model yielded CI values of 0.58 and 0.71, respectively, mathematically proving synergism.