Then, we excluded proteins based on (a) a different trend in the WPMY‐1 co‐culture system compared to the primary screen, despite their significant biological roles in tumourigenesis and progression (BDNF [31], IL‐6sR [32], TGFα [33] and IL‐6) (Table S6), or (b) lack of novelty, reflecting well‐characterised roles in cancer, such as CXCL1, CCL2, CCL5, IL‐6 and IL‐8. Here, CCL5 is linked to cancer.