CTSD and neuroblastoma: The structural organization and physiological characteristics of tumor spheroids strongly influence the response to therapy, the cell signaling pathways, and the profiles of gene and protein expression.31 Recently, our group demonstrated that the expression of the lysosomal protease cathepsin D (CD) is differentially modulated between 2D and 3D cell culturing, and this reflects on the survival efficiency of neuroblastoma (NB) cells.