Proline Quantification in HaCaT Cells

Proline concentration in culture HaCaT cells was measured with the use of the method published by Klupczynska et al. [46 (link)]. Samples were analyzed using Agilent 1260 Infinity HPLC system coupled to Agilent 6530 Q-TOF mass spectrometry detector (Agilent Technologies, Santa Clara, CA, USA) with electrospray ionization as an ion source in positive ionization mode. Samples were injected onto a HILIC column (Luna HILIC, 2 × 100 mm, 3 µm, Phenomenex, Torrance, CA, USA). Methanol—extracted cell lysates were collected in triplicates and injected in duplicates. Total protein concentration was used for normalization and presented as µM/µg protein.