HDAC9 and colorectal carcinoma: In this respect, our results are consistent with studies on other HDAC inhibitors demonstrating beneficial effects on the immune response, including effects on MHC gene expression [36, 52, 53, 54, 55, 56, 57] In malignant disease, the AP signature was absent in CRC stage IV disease, with a clear dichotomy evident between MSI status and MSS status, where MSS disease exhibited low expression of the AP signature in contrast to MSI.