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In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Context: It has been demonstrated that photodynamic therapy (PDT) is a promising treatment approach for hyperplastic dermatosis and results in a beneficial outcome. In the present study, PDT involving hematoporphyrin monomethyl ether (HMME) was applied to keloid fibroblasts (KFB), and the effects and the mechanism of action were explored.', 'Keloid fibroblastic cells were divided into four groups (PDT group, light alone group, HMME alone group, normal cultured group). Cell proliferation and apoptosis were observed. Radical oxygen species (ROS) were detected by means of dihydroethidium (DHE) and dihydrorhodamine (DHR123). ROS in the PDT group were also assessed after addition of tiron.', 'Cell proliferation was inhibited in the PDT group (p < 0.05), while the rate of apoptosis was also clearly increased (p < 0.05). The levels of ROS were significantly higher in the PDT group than was observed in the other three groups (p < 0.05). With the addition of tiron the damaging effects were reduced.\Question: Is photodynamic Therapy-Induced Apoptosis of Keloid Fibroblasts Mediated by Radical Oxygen Species In Vitro?
Output:
Our data indicated that HMME-mediated PDT could inhibit keloid fibroblast proliferation and could also induce apoptosis. This process was associated with the production of ROS.