Overexpression of chemerin suppresses tumor growth. (A) Measurement by ELISA of secreted chemerin in conditioned media from control or RARRES2-transfected B16 melanoma cells. (B) FACS analysis of the surface phenotype of transfected B16 lines. (C and D) In vitro proliferation of RARRES2-transfected and untransfected, wild-type B16 melanoma cells (C) or after culturing with recombinant chemerin (D). (A, C, and D) Error bars represent SEM. (E and F) Clonal (E) and polyclonal (F) chemerin-expressing or control vector–transfected B16 cells were implanted subcutaneously into C57BL/6 mice, and growth was measured over time. Graphs are from a representative experiment of more than four performed with two independently derived chemerin-expressing clones (E) or independently generated polyclonal transfectant pools (F). Tumor size is represented as mean ± SEM, with cohorts of more than four mice per group. *, P < 0.05 comparing control versus chemerin-expressing tumors by two-tailed Student’s t test.