Leonardo da Vincis masterpiece the Mona Lisa is warping, Louvre museum officials said last week. Officials will X-ray the painting so they can pinpoint the source of the warp. The portrait was painted, in 1505, on a poplar board that has at least one major crack and is now bending. This isnt evolving the way wed like it to, said Vincent Pomarede, chief curator of paintings. One side is moving more, and faster, than the other. Pomarede said the warping was probably caused by strips of wood added to the back of the painting over the centuries to strengthen it. The Mona Lisa, viewed by some 6 million people a year, is displayed through bulletproof glass, in a humidity-controlled case. If we preserve her properly, Pomarede said, she will still be there 500 years from now.