NBA's George Mikan -- Rookie Card Sells for $400,000

At least one Lakers player is hot these days ... even though he's dead ... 'cause George Mikan's rookie card just sold for more than $400,000!!!!!

A rare Mikan 1948 Bowman rookie -- the ONLY one ever graded gem mint 10 by PSA -- was snatched up at the SCP Auctions' Fall Premiere auction for $430,664.

The craziest part ... the same card was bought back in 2009 for $225k ... so clearly, Mikan was one hell of an investment.

As for the buyer -- the auction house hasn't revealed the person's name.