QPCR-generated gene expression data for a set of 10 genes (CFLAR, DUSP1, IFNGR1, ITGAX, PBEF1, PSEN1, RNF130, RYBP, MAPK9, and NKTR), originally identified and validated in 458 peripheral blood samples from pediatric recipients of a renal transplant [11], were cross-validated in peripheral blood samples from 141 heart transplant recipients and demonstrated significant differences between rejection and non-rejection groups. This evidence concerns the gene MAPK9 and cardiac transplant.