MMP9 and psoriasis: Analysis of protein–protein interactions among the psoriasis-related chemokine targets was performed using a string database, and the result is shown in Figure 2B. The black-to-blue nodes in the middle represent the top 10 genes with the largest degree values (i.e., TNF, AKT1, SRC, CASP3, ESR1, MMP9, PPARG, PIK3R1, CDC42, and RELA), which play a key role in the core target of KP (Figure 2C).