MMP3 and neoplasm: Both tumor foci in the lungs and weights of the lungs from mice that received MMP3KD 3T3-A-EXO-treated 3LL cell transfer were reduced compared with mice that received NC 3T3-A-EXO-treated 3LL cell transfer (Figure 5C, 5D), suggesting that MMP3 promoted 3T3-A-EXO-mediated 3LL tumor cell metastasis in vivo.