Additional file 4. pIL-11 treatment and knockdown did not affect cell viability. (A) Cell viability was determined by CCK-8 assay after treatment of the Vero E6 cells with different concentrations of pIL-11 for 18 h. (B) NC and IL-11 KD Vero E6 cells were plated and culture to 70% confluent monolayers for the CCK-8 assay