KRIT1 and breast carcinoma: However, mPR-specific inhibition of protein expression of CCM1/3 in nPR (+/−) ECs (Figure 1D) is more dramatic than what was observed in either nPR(+/−) breast cancer cells [5,7,8,16], suggesting that mPR-specific PRG actions have a stronger effect on the stability of the CSC in microvascular ECs.