In a mother substrate for a lower substrate, a substrate for a display panel and a method of manufacturing a display panel, the substrate for the display panel includes a lower substrate and an upper substrate facing the lower substrate. The lower substrate includes an inspection line that receives a first inspection signal externally provided, a gate driving part that outputs a second inspection signal in response to the first inspection signal from the inspection line, and a pixel part driven in response to the second inspection signal. The inspection line is disposed on a grinding area. Thus, the display panel may have an enhanced productivity and an improved yield, on which the gate driving part is formed.