A Closer Look at Metalloproteinases first presents an analysis of the matrix metalloproteinases system in two common neurodegenerative disorders, namely age-related macular degeneration and Alzheimer's disease. Next, this collection aims to evaluate the expression of matrix metalloproteinase-9 in nasopharyngeal carcinoma patients. The cross-sectional analytic study enrolled 106 patients with nasopharyngeal carcinoma based on radiologic and histopathological examination. The patient never underwent radiotherapy, chemotherapy and/or a combination. Matrix metalloproteinase-9 was assessed using immunohistochemical staining of matrix metalloproteinase-9 in the anatomic pathology department. The authors go on to discuss the matrix metalloproteinases family, their structural organization, functions and role in cardiovascular disease. Data about the role of matrix metalloproteinases in the pathogenesis of psoriasis is summarized. In psoriasis, matrix metalloproteinases facilitate structural remodeling of the epidermis that, in turn, results in the development of psoriatic plaques. Additionally, pregnancy is a very peculiar event in which the uterus undergoes intense morphophysiological modifications, especially related to vascular remodeling and angiogenesis, as well as trophoblast invasion, which occurs in early pregnancy period until reaching maternal spiral arteries and replacing the endothelium forming the endovascular-trophoblast. Such vascular modifications ensure the high-flow and low-pressure blood supply to the developing fetus, which in turn requires more and more space, causing the uterus to become enlarged and distended. In this context, an orchestrated regulation of matrix metalloproteinases and their endogenous inhibitors is essential for proper gestational development. In the penultimate chapter, tissue components, matrix metalloproteinases properties and functions, bone modelling, remodelling and resorption, repair and regeneration, and pathological bone resorption are discussed. The concluding chapter explores the way in which protein tyrosine phosphatases are important targets that are known to play a key role in the development of chronic degenerative diseases such as obesity, diabetes, and some neurological diseases.