Hollenberg AM, Maqsoodi N, Phan A, et al. - This study was sought to explore ALK3, BMP-2, pSMAD1/5/8, and matrix metalloproteinase (MMP)-13 expression in intervertebral disc (IVD) specimens collected from patients undergoing surgery for disc degeneration, to correlate Activin receptor like-kinase 3 (ALK3), bone morphogenic protein (BMP)-2, pSMAD1/5/8, and MMP-13 expression in IVD specimens to the 5-level Pfirrmann MRI grading system, and to compare ALK3, BMP-2, pSMAD1/5/8 and MMP-13 expression between cervical and lumbar degenerative disc specimens. Researchers designed an immunohistochemical study evaluating ALK3, BMP-2, pSMAD1/5/8, and MMP-13 expression levels in human control and degenerative IVD specimens. They obtained human IVD specimens from surgical individuals who had undergone discectomy and interbody fusion at our institution between 1/2015 and 8/2017. For this analysis, 52 individuals were included; nevertheless, 2 control and 2 degenerative patients were excluded due to incomplete data sets. The data exhibited that in the human degenerative specimens, BMP-2 and pSMAD1/5/8 signaling activity was significantly upregulated, while ALK3 and MMP-13 expression were not significantly changed. The outcomes of this study demonstrated that the expression levels of BMP-2 and pSMAD1/5/8 associate positively with the degree of disc degeneration assessed according to the Pfirrmann MRI grading system.