TASK DEFINITION: In this task, you are given a sentence in the Spanish language. Your task is to translate the Spanish sentence into the English language.
PROBLEM: Es una molécula coestimuladora que se expresa en las células presentadoras de antígeno

SOLUTION: It is a costimulatory molecule that is expressed in the antigen-presenting cells

PROBLEM: Al disolver un soluto no volátil en un disolvente formando una disolución diluida, se observa

SOLUTION: When dissolving a non-volatile solute in a solvent forming a diluted solution, it is observed

PROBLEM: El segundo ruido cardíaco coincide con

SOLUTION:
The second heart sound coincides with