A 3,4-diaryl pyrazoloresorcinol compound that inhibits the Hsp90 ATPase activity with IC50 values of 3.2 and 6.6 μM for human Hsp90β and yeast Hsp90, respectively; induces Hsp72 expression and decreases the expression of oncogenic client proteins such as c-Raf, ErbB2, and Cdk4 in SKMEL 28 melanoma cells