What roles do cyclooxygenase, lipoxygenase, and epoxygenase have in signal transduction?
I just took a quick look.

These classes of enzymes are important to a family of lipid based molecules which perform intra and intercellular signalling with a lot of medical importance. 

Epoxygenases can create epoxides of arachidonic acid,  which can modulate cell proliferation.  Arachidonic acid is a well known second messenger in many tissues in the cell, so these enzymes clearly would affect many signalling pathways. 

Cyclooxygenases (COX) enzymes are such important mediators of inflammation signalling that they are the primary targets of aspirin and other Non steroidal anti-inflammatory drugs. 

Lipoxygenases oxygenate compounds such as prostaglandins which are downstream from aranchidonic acid (as does COX).