The invention provides methods for determining whether a subject is suffering from a rheumatoid arthritis associated with the BRAF oncogene comprising contacting isolated fibroblasts from the subject with a molecule or pool of molecules directed to the BRAF oncogene and culturing the sample in the presence of the agent and determining whether BRAF oncogene expression by the cell is decreased and/or whether cells in the sample return to a less transformed phenotype, exhibit decreased cell proliferation and/or exhibit increased contact inhibition, any of which is indicative that the subject is suffering from a rheumatoid arthritis associated with the BRAF oncogene.
