sample treatment expression 1 alpha 550 2 alpha 504 3 alpha 543 4 alpha 1365 1 gamma 567 2 gamma 572 3 gamma 562 4 gamma 1380 1 combo 602 2 combo 599 3 combo 575 4 combo 1400 1 none 525 2 none 530 3 none 499 4 none 1325