SL 0101-1

The p90 ribosomal S6 kinases (RSK) 1-4 are downstream members of the extracellular signal-regulated kinase (ERK)/MAPK cascade. SL 0101-1 is a kaempferol glycoside, isolated from the tropical plant F. refracta, that selectively inhibits RSK2 with an IC50 value of 89 nM (Ki = 1 ?M) without interfering with upstream activators of RSK, including ERK, MEK, EGFR, and PKC.{22410} At 100 ?M, SL 0101-1 inhibits the proliferation of MCF-7 breast cancer cells, arresting cells in the G1 phase of the cell cycle.{22410} SL 0101-1 has been used to characterize the intracellular signaling events associated with angiotensin II-induced tyrosine kinase activation with a concentration of 30 ?M attenuating angiotensin II-induced cell proliferation.{22411}