Private equity funding

Hi All,

XYZ Co. Pvt. Ltd. has 4 promoters, each holding 25% Stake. The company's Capital is 1 lakh. 

Now, Private Equity wants to invest in the above company and they will take 15% Stake by paying Rs. 10 crores.

Whether the Promoter, who give up their stake will be liable to Capital Gain in the above case? 

If yes, what will be the liability of each of the Promoter assuming, all give up equal stake to Private Equity?

Thanks