Complex sentence: Reverse transcription polymerase chain reaction (RT-PCR) is one of many variants of polymerase chain reaction (PCR), in which the technique is commonly used in molecular biology to detect RNA expression levels.
Split into simpler sentences: Reverse transcription polymerase chain reaction (RT-PCR) is one of many variants of polymerase chain reaction (PCR). This technique is commonly used in molecular biology to detect RNA expression levels.