Can one travel with suitcases on the subway from the airport?

Thanks!

Can one travel with suitcases on the subway from the airport?

Yes.

For info, see here:

http://www.visitsingapore.com/publish/stbportal/en/home/getting_around/transportation/mrt.html

Yes.
It's not particularly convenient though, as you'll have to transfer at least once (and probably twice) to get to the city center, and not all stations have elevators yet (although they're busily working on fixing up the last few that don't). I do the trip regularly with a rollaboard, but would hesitate with a fully loaded suitcase. Taxis are so cheap anyway that the savings is marginal.