STAT3 and Miyoshi myopathy: In contrast, different concentrations of cladribine were used in the combinational studies: 2 μmol/L for U266 cells, 1 μmol/L for RPMI8226 cells, and 0.2 μmol/L for MM1.S cells, because treatment with cladribine at this concentration for 24 hrs did decrease P-STAT3 levels (Figure 5), but had no significant induction of caspase activation and PARP cleavage for each of the three MM cell lines (Figure 4).