Chromatin Immunoprecipitation (ChIP) Assay

S3-NTDi treated and untreated MB cells were protein-protein cross-linked with Disuccinimidyl glutarate (DSG), followed by protein-DNA cross-linked with formaldehyde, as described previously [26]. Cells were then lysed and sheared chromatin were immunoprecipitated with either STAT3 Ab or IgG, following instructions from Pierce Magnetic ChIP Kit (#26157). Quantitative genomic PCR was performed in QuantStudio 3 Real-Time PCR System, using human Bcl-2 promoter and CCND1 promoter primers (#12924, #12531) from Cell Signaling. Data were corrected for variations in input and expressed as fold change relative to IgG controls.