KRAS and neoplasm: In contrast, treatment with CTX alone showed a negligible effect on MIA PaCa-2 and PANC-1 viability, consistent with the known resistance of KRAS mutant tumours to this antibody.20 Similar trends were also noted following cell survival analysis by clonogenic assay, in which treatment with CTX-MMAE led to a concentration-dependent reduction in the colony-forming ability of both MIA PaCa-2 and PANC-1 cells (Fig. 2c, d).