Maintaining an appropriate balance between excitation and inhibition is critical for information processing in cortical neurons. It is known that cortical neurons receive widely disparate levels of excitation. To ensure efficient coding, they are capable of cell-autonomously adjusting the inhibition they receive to the individual levels of excitatory input, but the underlying mechanisms are not understood. The article associated with this data shows that Ste20-like kinase (SLK) in cortical neurons mediates cell-autonomous regulation of excitation-inhibition balance in the thalamocortical feed-forward circuit, but not in the feed-back circuit. The parallel reaction monitoring data here supports the link between activity, SLK phosphorylation and function.