Crane showed that B7-H1 expression and function in breast and prostate cancer was mediated by the PI3K pathway.7 B7-H1 expression was shown to be dependent on the ERK and p38 mitogen-activated protein kinase (MAPK) signaling pathways in colon cancer8, in anaplastic large cell lymphoma and Hodgkin lymphoma.9 Our study suggests that the ERK 1/2 pathway and resultant increase in B7-H1 transcription are involved in HCMV-induced B7-H1 regulation in trophoblast cells. Here, CD274 is linked to prostate cancer.