Extracellular media conditioned by HA‐GFP or HA‐IKKε expressing Flp‐In 293 cells was collected and applied on three different receiving cell lines: Flp‐In 293 HA‐GFP, not expressing IKKε (Fig EV4A) and the T47D and ZR‐75‐1 breast cancer cell lines, constitutively expressing IKKε (Fig EV4B and C). This evidence concerns the gene IKBKE and breast cancer.