*2.1. Cell Lines and Cell Treatments*

Normal human epidermal cells (HEKa-ATCC PCS 200-011) and dysplastic keratinocytes (DOK-ECACC) were cultivated in standard cell culture conditions (37◦C, 5% CO2) according to manufacturer instructions regarding cell culture media and supplements. The sea-buckthorn oil was a cold-pressed, commercially available product of Romanian origin and stored as 1/10 DMSO solution. Further dilutions were made with complete cell culture medium and appropriate controls containing a comparable dilution of DMSO. Cells were exposed to UVA with a UV-365 nm lamp (VL-340 BLB model—Vilber Lourmat, France) at a light intensity of 381 µW/cm<sup>2</sup> , for 30 min, in a laminar flow hood, as previously described [17].
