GTKO pAEC were activated using thrombin (40U/mL), pIFN-γ (40U/mL), or hIFN-γ (200U/mL) for 24h. SLA class II expression was upregulated only after pIFN-γ activation, but not after thrombin or hIFN-γ activation. There was no change in SLA class I expression after activation. Data are representative of three different experiments. (Reproduced from Ezzelarab C, et al, Xenotransplantation 2012; 19:311-316 [33] with permission).