FIGURE 3.

Inhibition of SPRK1/2 by SRPIN340 prevents the down-regulation of VEGF_xxxb by IGF. A–D, cells were treated with SRPIN340 (10 μm) alone or in combination with IGF-1 (100 nm). A, RT-PCR showed that SRPIN340 reduced the VEGF₁₆₅:VEGF₁₆₅b ratio at the RNA level. B, Western blot demonstrating that SRPIN340 inhibited the IGF-mediated down-regulation of VEGF_xxxb expression at the protein level. C, ELISA results confirming that SPRIN340 specifically attenuates the IGF-1-dependent down-regulation of VEGF_xxxb, but did not affect endogenous expression of VEGF_xxxb. D, ELISA of the protein extract shows that SRPK1 transfection reduces VEGF_xxxb expression, and total VEGF expression. SRPK2 reduces total expression, but did not affect VEGF_xxxb expression.