GSK2118436 is an orally administered, potent and selective small molecule BRAF inhibitor that is currently being developed for the treatment of BRAF mutation-positive tumors. This is an open-label, non-randomized study designed to determine the absolute bioavailability of an oral dose of 150 mg of GSK2118436 co-administered with an intravenous 50 microgram dose of [14C]GSK2118436 in subjects with BRAF mutant solid tumors. Pharmacokinetic samples will be obtained up to 72 hours post-dose. Safety assessments will be performed throughout the study. After completing all assessments, eligible subjects may transition to BRF114144, an open-label, rollover study of GSK2118436 to continue treatment.