Post edited 10:40 pm - 06/12/2009 by Rook

Dear Sharath, you've grasped the central idea - which is that the apostrophe is to be used only if you want to indicate a possessive noun.

So, for the example you've mentioned, the apostrophe is not needed. You just need to write MPs.

Here are more examples:

The MP will attend the meeting. (singular noun)
The MP's itinerary is yet to be confirmed.(singular possessive noun)

The three MPs will attend the meeting. (plural noun)
The three MPs' iteneraries are yet to be confirmed. (plural possessive noun that ends in "s")

Note: when a plural possessive noun ends in "s", you don't need to add an additional "s" after the apostrophe.
Parents' concerns. (i.e., the concerns of many parents)
Workers' grievnces. (i.e., the grievances of many workers)
However, when a plural possessive noun doesn't end in an "s", you do need an "s" after the apostrophe:
Children's day. (plural noun not ending in "s")
Women's hostel. (plural noun not ending in "s")