The expansion of fibroblasts is seen in the early tumour stage where CAFs act as “tumour suppressors”, producing gap junctions which subsequently turn CAFs into “tumour promoters”, as activated by tumour-secreted factors such as PDGF, FAP, interleukin-4, interleukin-6 and prostaglandin E (PGE) [49,50]. This evidence concerns the gene IL4 and neoplasm.