KARACHI                  -              Pakistan Tehreek-e-Insaaf (PTI) Karachi Division President and Member Sindh Assembly Khurrum Sher Zaman paying tribute to the martyrs of May 12, 2007 incident, said that they laid their lives for the uplifting of constitution. In a message, he said the day was one of the darkest day in the his­tory. Khurrum Sher Za­man said the PTI stands by side of the families of victim of May 12.