SPRY2 and Miyoshi myopathy: Furthermore, using western blotting, it was identified that the expression level of SPRY2 was significantly lower in the RPMI 8226 and KM3 MM cell lines, which have high endogenous miR-21 expression levels, whereas the level of SPRY2 was significantly higher in the U-266 cell line with low endogenous miR-21 expression.