CDKN2A and freckles: Kwon et al. (2021) showed that bipolar RF device treatment reduces the number of p16INK4A-positive senescent fibroblasts and increases the expression of HSP70 and HSP90 in melasma skin. More recently, fractional RF microneedling devices that deliver targeted bipolar RF energy directly to the reticular dermis via microneedles have been developed. Fractional RF microneedling devices have also shown to be effective in treating UV-induced hyperpigmentation by upregulating the anti-senescence pathways (Rangarajan et al., 2013; Yoon et al., 2018; Lee et al., 2021).