Melt margarine in a frying pan over medium heat.
Brown liver well on both sides.
Saute' mushrooms in small amount of margarine for few minutes and then add to liver.
Also add parsley, lemon juice and wine.
Cover and cook slowly, turning liver occasionally, until tender, 10 to 15 minutes.
Add more wine during the cooking, if necessary, to keep it moist.
Add salt and pepper to taste.
Serve immediately with the pan juices spooned over it.