Data Supplement

• Supplemental Data -

  Supplementary Figure S1: The results of SEC-HPLC of 5 selected antibodies under natural conditions. Except for 1B4, which has the ability to form polymers, most of the other antibodies are in the form of monomers.

  Supplementary Figure S2: Fitting graph of association/dissociation of the three candidate antibodies. The KD values of each antibody were listed as showinthegraph.

  Supplementary Figure S3: Analysis of blocking activity between candidate antibodies and differentgands of Siglec-15.

  Supplementary Figure S4: Evaluation of the biological activity of candidate antibodies invitro.

  Supplementary Figure S5: The expression level of EGFR on the cell surface of H157(S15⁺).

  Supplementary Table S1