Fig 2: FAM167A and surface DSG1 levels are associated with BCR-ABL-independent TKI resistance in CML patients. A qRT-PCR analysis of FAM167A mRNA expression in CD34+ stem/progenitor cells from imatinib-responsive CML patients (S) at the time of diagnosis (n = 26) and at follow-up (n = 26), in imatinib-resistant CML patients (R) without BCR-ABL mutation at the time of diagnosis (n = 12) and at follow-up (n = 11), and in imatinib-resistant CML patients harboring a BCR-ABL mutation at the time of diagnosis (n = 10) and at follow-up (n = 12). Imatinib resistance and BCR-ABL mutation status were determined at follow-up. The level of FAM167A was normalized to that of GAPDH. B Relative surface expression of DSG1 (MFI) in CD34+ stem/progenitor cells from imatinib-responsive CML patients at the time of diagnosis (n = 8) and at follow-up (n = 8), and from imatinib-resistant CML patients without BCR-ABL mutation at the time of diagnosis (n = 10) and at follow-up (n = 7), as measured via flow cytometry. C Proposed model showing involvement of the FAM167A-induced noncanonical NF-?B pathway in BCR-ABL-independent TKI resistance. Unpaired two-tailed t-test; *P < 0.05, ***P < 0.001. NS, not significant

Fig 3: FAM167A binds to its receptor DSG1. A Surface FAM167A receptor (FAM167AR) staining of K562S and K562R cells using Myc-tagged FAM167A and an Alexa Fluor 488-conjugated anti-Myc antibody. B Silver staining of immunoprecipitated samples prepared from K562R cells using Myc-tagged FAM167A and an anti-Myc antibody bound to Protein G Sepharose® beads. C MS/MS spectrum and peptide sequence of the indicated band from B. D Co-immunoprecipitation analysis between FAM167A and DSG1 in K562R cells. E qRT-PCR analysis of DSG1 mRNA levels in K562S and K562R cells, and in K562R cells treated with 1 µM imatinib for 24 h. F Immunoblot analysis of DSG1 expression in K562S and K562R cells. G Surface staining of K562S and K562R cells using an anti-DSG1 antibody. H Immunofluorescence microscopy analysis of DSG1 expression in K562S and K562R cells. Nuclei were visualized using Hoechst 33342. Scale bars, 10 µm. GAPDH was used as an internal standard (F). IP, immunoprecipitation. MFI, mean fluorescence intensity. Data are representative of three (A, B, D-H) independent experiments (error bars, s.d. of duplicate (E) or triplicate (A, G) samples). Unpaired two-tailed t-test; **P < 0.01, ***P < 0.001. NS, not significant