FOSL1 and cancer: To further confirm the importance of PRSS3, PAR2, and FOSL1 in promoting invasion and cancer metastasis, we overexpressed these three genes in A549‐C3 cells, which are the parental cells of A‐SSP6 cells and had low levels of PRSS3, PAR2, and FOSL1 (Figure S8A, Supporting Information).