B cells with activated Stat3 accelerate tumor progression and increase blood vessel formation in tumors.

<p>(<b>A and B</b>) Left, Growth curve of B16 (<b>A</b>) or LLC (<b>B</b>) tumors in <i>Rag1^−/−</i> mice, without or with <i>Stat3^+/+</i>or <i>Stat3</i>^−/− B cells. B cells were enriched from splenocytes of B16 or LLC tumor-bearing mice with or without <i>Stat3</i> ablated in hematopoietic cells; <i>n</i> = 8; ***, <i>P</i><0.001. Middle, Immunofluorescent staining of tumors to detect microvessels (anti-CD31, red) and nuclei (Hoechst, blue); scale bars, 200 µm. Right, Graph showing the number of CD31⁺ vessels in the tumor tissues (3 microscopic fields/section); means ± SD, <i>n</i> = 2. (<b>C</b>) Representative images (left) and a graph (right) showing the number of spontaneous lung metastatic nodule in mice with <i>Stat3^+/+</i> or <i>Stat3^−/−</i> B cells receiving B16 tumor cells; means ± SEM, <i>n = </i>5.