MX1 and neoplasm: Interestingly, the inhibition was lower in three out of the four MPM cell lines that express IFN-α, IFN-β and Mx1 constitutively (Meso34, 36 and 37), whereas the inhibition was more profound in tumor cell lines that did not develop a type I IFN response in the presence of the virus, such as Meso31, 47, 76, 225 and 11.