FIGURE 4.

Leukotriene modifiers. Cell activation increases intracellular Ca²⁺ ions, leading to association of cPLA₂α with the nuclear membrane, generating arachidonic acid. This activates 5-LOX, which is also located in the nuclear membrane bound to FLAP. This generates LTA₄, which is converted by membrane-bound LTC₄ synthase (LTC₄S) in cells, such as mast cells and eosinophils, into LTC₄, LTD₄, and LTE₄, which then activate CysLT₁ receptors on target cells, such as airway smooth muscle cells. This pathway may be blocked by various types of drugs shown in green boxes.