Basal-like breast cancers are commonly negative for expression of estrogen and 
progesterone receptors and HER-2 (triple-negative breast cancer), which makes 
this subtype of breast cancers more aggressive and less responsive to standard 
treatment. We have applied a small-scale chemical proteomics method using 
bisindolylmaleimide (Bis) class of protein kinase C inhibitors to study the 
Bis-binding proteome in a cell culture model of basal breast carcinoma 
(MDA-MB-231). Using MS, we identified 174 proteins captured by the Bis-probe in 
phorbol ester (PMA) stimulated cells. Gene ontology analysis broadly categorised 
these proteins as ATP binding (42%), GTP binding (6%) and having 
nucleoside-triphosphatase activity (21%). Of the 64 enzymes captured by the 
Bis-probe, the majority had either ATP and/or nucleotide binding functions. Two 
previously unreported Bis binding protein kinases, serine/arginine-rich 
protein-specific kinase 1 (SRPK1) and interferon-induced RNA-dependent protein 
kinase (PKR) were observed. We then incorporated SILAC for quantitation to 
examine the proteins that were differentially captured by the Bis-probe 
following 30 and 60 min PMA stimulation. This provided novel evidence for PMA 
regulation of the enzymes glyceraldehyde-3-phosphate dehydrogenase, nucleolar 
RNA helicase 2 and Heterogeneous nuclear ribonucleoprotein M.