Tumor-promoting activity of macrophages is mediated through IL-1β. Primary mouse macrophages primed by LPS (100 ng/ml) were stimulated with ATP (5 mM) for 1 hr in the presence of isotype control IgG or anti-IL-1β antibody (10 μg/ml). Conditioned culture supernatants were collected and added to the bottom chambers of transwells which had B16F10 cells plated in the upper chamber. After 24 hr, cell migration and invasion were determined. (A) Images of B16F10 cell migration. (B) The number of migrating B16F10 cells was counted in the microscopic field. (C) Images of B16F10 cell invasion. (D) The number of invading B16F10 cells was counted in the microscopic field. Values are means ± SEM (n = 5). *p < 0.05.