This suggests that the ALF-conditioned media induced the SCLC cells to secrete more GRO-α, IL-8, and MMP-1 and these factors all play key roles in angiogenesis and tumor metastasis (Zhu et al., 2004; Morishita et al., 2018; Shengnan Yu et al., 2020). This evidence concerns the gene MMP1 and small cell lung carcinoma.