The invention provides compounds, methods, pharmaceutical compositions, and kits for the treatment of proliferative disorders such as cancer. In one aspect, the methods comprise compounds that inhibit the activity of protein kinases, such as cell division cycle (Cdc) kinase. In another aspect, the methods comprise compounds that inhibit Cdc7 and/or Dbf4 activity. In another aspect, the methods comprise compounds that exhibit antiproliferative properties useful in treating diseases such as cancer. Compounds useful for any of the methods include compounds of the Formula (A) or (B): or pharmaceutically acceptable salts thereof. Exemplary compounds of Formula (A) or (B) include granaticin A, granaticin B, dihydrogranaticin A, dihydrogranaticin B, medermycin, and actinorhodin.
