COL4A2 and keloid: Compared to the normal skin model, the in vitro keloid scar model showed an increased contraction, dermal thickness (trend) and α-SMA staining, as well as decreased secretion of HGF and decreased dermal expression of the ECM-related genes COL4A2, HAS1 and MMP3. Although the keloid scar model co-cultured with monocytes showed the same increased contraction and α–SMA expression with a trend towards increased dermal thickness, in this current study there was no further exaggeration of the keloid phenotype as we had hypothesized.