Early Alterations of Actin in Cultured Human Keratinocytes and Fibroblasts Exposed to Long‐wavelength Radiations. Possible Involvement in the Uva‐induced Perturbations of Endocytotic Processes

Exposure of cultured MRC5 human fibroblasts or NCTC 2544 human keratinocytes to mild doses of ultraviolet A (UVA: 320-400 nm) radiations markedly decreased the actin reactivity with fluorescein-labeled phalloidin. This indicates a change in the degree of polymerization of actin and thus in the organization of actin filaments. Such a phenomenon might be involved in the previously reported UVA-induced inhibition of specific and nonspecific endocytotic processes.