MMP2 and melanoma: In 2017, Sheng Pan and co-workers first reported that Cleistanthin A (Figure 5) blocked the invasion and metastasis of human melanoma cells (A537) by inhibiting the expression of matrix metallopeptidase-2 and -9 (MMP-2, -9) in dose-dependent (0.03, 0.1, and 0.3 μM concentrations, at which cell viability was not affected) and time-dependent manners.