For anybody interested in this question, here is reply I got courtesy of KDKSAIL :-

Nanterre is a near northwestern suburb of Paris. NANTERRE VILLE station is on the RER 'A-1' (Saint Germain-en-Laye) ligne.

From the BVA shuttle stop, you will have to walk down Blvd. Pershing to the PORTE MAILLOT Metro station and take the #1 Metro ligne from PORTE MAILLOT (heading in the direction of Château de Vincennes) to CHARLES DEGAULLE-ÉTOILE station (2 stops) and then switch over to the RER 'A-1' ligne (heading in the direction of Saint Germain-en-Laye or Le Vésinet-Le Pecq) to NANTERRE VILLE station (10 mins...one-Way fare from PORTE MAILLOT METRO to NANTERRE VILLE RER will be 2,20€.

The only '..trick..' to this transfer is that at the CHARLES DEGAULLE-ÉTOILE station you need to make sure that you take the correct RER 'A' ligne train---any 'A' train with four-letter, '..X xxx..' (heading in the direction of Le Vésinet-Le Pecq), or '..Z xxx..' (heading in the direction of Saint Germain-en-Laye) designations. Train frequency will be approx. 1-every-10-mins. during most of the day and evening).

Nanterre and NANTERRE VILLE station are located out in Transportation Zone 3 from central Paris...so you will need either a separate RER ticket (fare: 2,20€) or a transportation pass valid for Zones 1-3 travel.

When coming back into Paris from Nanterre, there will be RER 'A' ligne stations located across the city (Charles deGaulle-Étoile; Auber, Chatelet-Les Halles, Gare de Lyon) where you may begin from or transfer over to other regular Metro lignes to get where you want to go.

baz.