Y27632 and diltiazem selectively promote axon regeneration in the presence of CSPG. A, βIII-tubulin immunostaining of cortical cultures after five days of regeneration under the indicated conditions. B, Quantification of axon regeneration. The combination of Y27632 + diltiazem increases axon regeneration 2.2-fold compared with the CSPG control. Y27632 and diltiazem, alone or in combination, do not affect cortical axon regeneration in the absence of inhibitor. Data are mean ± S.E. n = 11-24. Scale bar, 100 μm. *, p < 0.05; ****, p < 0.0001, two-way ANOVA, post hoc Tukey.