Is Wine Necessary to the Lord's Supper?

Some believers think that using grape juice for the Lord's Supper is unbiblical, but is it? Using my faithful BibleGateway.com, I searched for wine (Greek: οινος) and found no references to the Lord's Supper. All I can find is "the cup" (Matt. 26:27; Mark 14:23; Luke 22:17,20; 1 Cor. 10:16,21; 11:25-27) and "the fruit of the vine" (Matt. 26:29; Mark 14:25; Luke 22:18). Although I myself believe in the legitimacy of taking alcoholic beverages based on the clear testimony of Scripture (Lev. 10:19; Deut. 11:14; Psa. 104:15; etc., etc.), despite the warnings associated with its consumption, I have to say that those who insist that wine is necessary have no Scriptural warrant.

The fact that it is the redness of "the fruit of the vine" that signifies the blood and that alcohol signifies nothing should be enough for those who berate the weaker brethren.

(This is the hyperlink for Keith Mathison's articles entitled "Protestant Transubstantiation: Examining the Use of Grape Juice in the Lord's Supper" quoted by Phil in the comments section. His articles are half-way down.)