(A) B16-F1 cells transfected with an empty vector or a GDF3-expressing vector. Twenty-four hours after the transfection total RNA was extracted and RT-qPCR was performed to measure the Id1 expression. "N.S." stands for not statistically significant. (B, C) B16-F1 (B) or B16-F10 (C) cells were transfected with empty or GDF3-expressing vectors. Twenty-four hours after transfection cells were injected subcutaneously into C57BL/6 mice. Tumors were excised 7, 10, and 14 days after injection. Total RNA was extracted from tumors or cell from culture (day 0) and RT-PCR was performed. (D, E) B16-F10 cells were transfected with empty (D) or GDF3-expressing vectors (E) and 24 hours after the transfection cells were injected subcutaneously into C57BL/6 mice. The B16-F10 tumor was excised 7 days after injection. Cells were stained with a FITC-conjugated anti-CD24 antibody and a PE-conjugated anti-CD44 antibody. Cells were analyzed by FACS. One of three similar experiments is shown.