Phosphatase regulation of immunoreceptor signaling in T cells, B cells and mast cells

• Phosphatases can regulate cell activation both negatively and positively.
• The biological effects of phosphatase activity are cell type specific.
• Phosphatases can regulate cell activation by acting as adaptors.

Recent progress has begun to reveal the often complex and changing roles of phosphotyrosine and phosphoinositide phosphatases in regulation of immunoreceptor signaling. The resultant confusion has been further increased by discoveries of new players. Here we provide a review of recent progress in defining the roles of these enzymes in immunoreceptor-dependent mast cell, T cell and B cell activation.