According to the eight studies, the underlying mechanisms of animal toxins against endometriosis were as follows: induction of apoptosis [28,29,30], inhibition of angiogenesis [31,32], reduction of estrogen level [27], suppression of matrix metalloproteinase (MMP)-9 expression [34], and anti-inflammatory effect [33] (Table 2). The gene discussed is MMP9; the disease is endometriosis.