The purpose of this study is to determine the safest dose of the multiple Raf kinase
inhibitor (including c-Raf, B-Raf, and the activated mutant B-RafV600E) XL281, how often it
should be taken, and how well subjects with cancer tolerate XL281. This study will also
determine how the body reacts to XL281 when it is taken with and without food, and with and
without Pepcid (famotidine), a drug that inhibits stomach acid production.