  We consider the effect of quantum interactions on Pauli-Fierz massive
gravity. With generic graviton cubic interactions, we observe that the 1-loop
counterterms do not conform to the tree level structure of Pauli-Fierz action,
resulting in the reappearance of the 6th mode ghost. Then to explore the
quantum effects to the full extent, we calculate the resummed graviton
propagator with an arbitrary interaction and analyze its complete structure,
from which a minimal condition for the absence of the ghost is obtained.
