XIAP and adrenal cortex carcinoma: Because we observed reduced XIAP expression in ACC cells treated with flavopiridol and carfilzomib, we assessed XIAP expression in ACC xenografts by immunohistochemistry and found lower expression of XIAP in ACC xenografts treated with the combination of flavopiridol and carfilzomib compared to other groups (p<0.01) (Figure 5B).