Given a passage with a question and an answer to that question, classify if the answer actually answers the question into 'yes' or 'no'. Output 'yes' if the answer answers the question and output 'no' if the answer does not answer the question.

Question: Is cytokeratin 20 a tissue-specific marker for the detection of malignant epithelial cells in the blood of colorectal cancer patients?
Answer: The lack of colon tissue-specificity renders ck20 useless as a marker for the post-operative surveillance of colorectal cancer patients.
no