Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:To examine whether these signaling pathways were involved in lung tumor exosome-mediated adipogenic inhibition of hAD-MSCs, we blocked these signaling with respective pathway inhibitor SB431542 [18], SP600125 [19], LY294002 [20], U0126 [21], and SB203580 [19] followed by tumor exosome treatment.
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