My gene knockout MEFs grow faster than wild type MEFs, and its differentiation ability towards adipocyte was strikingly increased. However, when I knockdown this gene, no matter in 3T3L1, C2H10T1/2 or C2C12 cells, all RNAi cells grow slower than control RNAi cells. Does anybody know something about this? Is this gene more important for immortalized cell line proliferation?