Acts 12:25
"And Barnabas and Saul returned from Jerusalem, when they had fulfilled their ministry, and took with them John, whose surname was Mark."
Cross References (ranked by relevance)
Acts 12:12
And when he had considered the thing, he came to the house of Mary the mother of John, whose surname was Mark; where many were gathered together praying.
Acts 15:37
And Barnabas determined to take with them John, whose surname was Mark.
1 Peter 5:13
The church that is at Babylon, elected together with you, saluteth you; and so doth Marcus my son.
Acts 4:36
And Joses, who by the apostles was surnamed Barnabas, (which is, being interpreted, The son of consolation,) a Levite, and of the country of Cyprus,