Although limited, a few studies suggest that ARLTS1 expression is downregulated in various types of human malignant disease, including prostate cancer,14 lung carcinomas, B cell chronic lymphocytic leukemia, ovarian carcinomas, and ovarian and breast cancer cell lines.4 The limited number of studies demonstrating ARLTS1 expression makes it difficult to comment further on this issue. This evidence concerns the gene ARL11 and prostate cancer.