The cytotoxic effect of 5-fluorouracil (5FU) and regorafenib (RF), drugs with different mechanisms of action used to treat colorectal cancer, on an HT29 cell line cultured on plastic or laminin 521 (LM-521) has been studied. It is first shown that LM-521 can increase the sensitivity of tumor cells to 5FU. A possible mechanism of the observed effect of LM-521 on the HT29 cell viability is proposed based on transcriptome and proteome analysis. The interaction of β1-containing integrins on the cell surface with LM-521 can activate the FAK/PI3K/Akt signaling pathways and promote phosphorylation of the YAP transcription coactivator and its binding to the complex with the 14-3-3σ protein. The formation of this complex leads to YAP retention in the cytoplasm and prevents its transport to the nucleus and the activation of antiapoptotic gene transcription.