All contrasts are WT-vs-KO:

#                       1    2     3       4       5     6     7       8       9     10    11    12       13    14       15    16    17    18    19      20 
#conditions = factor(c("KO2","KO2","KOIFN","KOIFN","Ko0","Ko0","KoIL4","KoIL4","Ko6","Ko6","wt0","wt0IL4","wt0","wt0IL4","wt2","wt2","wt6","wt6","wtIFN","wtIFN"))
col_ordering = c(11,13,5,6)#0h
col_ordering = c(15,16,1,2)#2h
col_ordering = c(17,18,9,10)#6h
col_ordering = c(19,20,3,4)#IFN
col_ordering = c(12,14,7,8)#IL4