K252b is an indolocarbazole isolated from the actinomycete
Nocardiopsis, first described as an inhibitor of protein kinase C.
1 However, as this compound does not freely pass through the cell membrane, it is used to inhibit extracellular kinases (ectokinases) of cells in culture.
2,3 K252b inhibits receptor-
mediated degranulation from basophil-
like RBL-
2H3 cells (IC
50 = 0.5 μg/ml) and human basophils.
4 This extracellular inhibitor is also used in comparison studies with the closely related, cell-
permeable inhibitor K252a, particularly in studies of neuronal differentiation.
5,6