EGFR and systemic sclerosis: Taken together with the finding that in VSMCs, a significant proportion of EGFRs and PDGFRs exist as heterodimers [13] and tests in our lab that show no significant difference in EGFR immunoprecipitation with SSc compared to control IgG (data not shown), we consider unlikely that anti-EGFR autoantibodies are responsible for our observations.