CD44 and cancer: CD44 also interacts with other highly relevant receptors such as TM4SF5, a tetraspanin involved in G1/S progression phase [31], osteopontin [32, 33], or CD74, the receptor for the macrophage migration inhibitory factor that induces the cleavage and release of its cytosolic extracellular domain which regulates cell survival [34]; this interaction activates signaling pathways involved in survival and proliferation of the cancer cells [35].