How do opponents of penal substitutionary atonement theory handle Isaiah 53?

How do opponents of the penal substitution theory of atonement handle Isaiah 53? This seems to describe penal substitution quite well: > 53:4 Surely he took up our pain and bore our suffering, yet we considered him punished by God, stricken by him, and afflicted. > > 5 But he was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was on him, and by his wounds we are healed. > > 6 We all, like sheep, have gone astray, each of us has turned to our own way; and the Lord has laid on him the iniquity of us all. (Isaiah 53:4-6, NIV)