hi, HaCaT usually secrets proinflammatory cytokines. for instance, IL6,TNF-a, etc and IL 20 belongs to Anti inflammatory group (IL10 family).
usually primary keratinocytes secrete IL20, and are responsible for skin inflammation in early stage.
there have been studies to understand the effect of IL20 on HaCaT cells.
trials could be done...activating keratinocytes would require K5 and K14. 'coz these are present in the basal layers and induce proliferation and differentiation. so, u can add TGF-beta which is a known and potent inducer for K5 AND K14. once they start proliferation,,,,u can proceed with IL20 stuff.