G3BP1 and infection: To determine whether HPIV3-induced SGs are cell-specific, we also examined the distribution of TIA-1 and G3BP in HEp-2 cells and MK2 cells infected with HPIV3 and found that both TIA-1 and G3BP were re-distributed into SGs and co-localized with each other, suggesting that SG formation is a general process during HPIV3 infection (S1B Fig).