The invention provides isolated anti-Pro115 antibodies that bind to Pro115. The invention also encompasses compositions comprising an anti-Pro115 antibody and a carrier. These compositions can be provided in an article of manufacture or a kit. Another aspect of the invention is an isolated nucleic acid encoding an anti-Pro115 antibody, as well as an expression vector comprising the isolated nucleic acid. Also provided are cells that produce the anti-Pro115 antibodies. The invention encompasses a method of producing the anti-Pro115 antibodies. Other aspects of the invention are a method of killing an Pro115-expressing cancer cell, comprising contacting the cancer cell with an anti-Pro115 antibody and a method of alleviating or treating an Pro115-expressing cancer in a mammal, comprising administering a therapeutically effective amount of the anti-Pro115 antibody to the mammal.