New Delhi,Dec 12: The bifurcation of Andhra Pradesh has taken a serious turn with all the four union ministers representing Andhra Pradesh threatening to quit.According to sources here on Saturday, the four union ministers Pallam Raju,Daggubati Purandeswari,Panabaka Lakshmi,and Sai Pratap are planning to quit the union cabinet in view of the latest developments in the state over Telangana issue.