SPRY2 and cancer: SPRY2 expression in cancer cell lines was inversely correlated with the IC50 values of all MEK inhibitors for the cancer cell lines (additional file 4: Fig. S1) with ρs ranging from − 0.24 to − 0.43 (all p-values <4E-08), indicating that cancer cell lines with higher SPRY2 expression are more sensitive to the MEK inhibitors.