Human-specific protein that acts as a key modifier of cortical connectivity in the human brain. Acts by inhibiting the functions of ancestral paralog SRGAP2/SRGAP2A, a postsynaptic protein that regulates excitatory and inhibitory synapse maturation and density in cortical pyramidal neurons. SRGAP2C is unstable but is able to heterodimerize with SRGAP2/SRGAP2A, thereby reducing SRGAP2/SRGAP2A levels through proteasome-dependent degradation.