RAC1 and carcinoma of esophagus: One study examining four amino amide local anaesthetics (lidocaine, ropivacaine, mepivacaine, bupivacaine) found that all substantially augmented the inhibitory effects of 5-fluorouracil in oesophageal cancer cells; this effect may be mediated through inhibition of mitochondrial respiration and Ras-related C3 botulinum toxin substrate 1 (Rac1), a member of the Ras family of GTPases which act as molecular switches to control cytoskeletal rearrangement and dysfunction of which is implicated in oncogenesis.42