The San Francisco 49ers signed tight end Asante Cleveland to the 53-man roster from the practice squad and released third-string quarterback Josh Johnson, the team announced Saturday.The promotion of Cleveland lends credence to the notion that neither starting tight end Vernon Davis, who did not practice this week after suffering left ankle and knee injuries Sunday night in the Niners' 28-20 loss to the Chicago Bears, nor backup Vance McDonald, who injured a right knee in that same game, will be ready to play in Sunday's NFC West matchup at Arizona.