In order to provide further evidence that the oxidized species of strep-MBP-ROXY9 indeed contains the expected disulfide between Cys21 and Cys24, strep-MBP-ROXY9 variants with either SCLC or CCLS sequences in the ‘active site’ were analysed (Supplementary Fig. 4a,b). This evidence concerns the gene MBP and small cell lung carcinoma.