Complex sentence: M2-PK is expressed in most human tumors Initially, a switch from PK-M1 to PK-M2 expression during tumorgenesis was discussed, but in clinical cancer samples, solely an up-regulation of PK-M2 could be confirmed.
Split into simpler sentences: M2-PK is expressed in most human tumors Initially, a switch from PK-M1 to PK-M2 expression during tumorgenesis was discussed. In clinical cancer samples, solely an up-regulation of PK-M2 could be confirmed.