Figure 9.

Differential effect of β_1C and β_1A integrin cytoplasmic variants on FAK, AKT, and MAP kinase pathways. The schematic drawings illustrate the β_1C effect on intracellular signaling pathways in response to exogenous and endogenous integrin engagement by fibronectin (Fn; A) or in response to either exogenous β_1C (B) or exogenous β_1A (C) ligation by TS2/16. The inhibitory effect of β_1C on Ras/ERK2, but not on FAK and AKT pathways, is shown in A. The failure of β_1C to induce ERK2 activation is shown in B. A previously described activation of the MAP kinase pathway by PI 3-kinase, downstream of Ras (King et al., 1997), is blocked in our model (A). It is also shown that AKT is activated in response to fibronectin (A), β_1C (B), or β_1A (C) engagement.