Figure 2. Collagen 1 promotes calcium influx and regulates cell survival by a calcium-dependent mechanism.

(A) Impact of decreasing extracellular Ca²⁺concentration on cell mortality of MCF-7 (a) and (b) T-47D cells. Mortality was measured 48 h post-starvation, with (+ Coll) or without collagen 1 (- Coll), after incubation with medium containing low (0.1 mM) or physiological Ca²⁺ concentrations (1.8 mM). Values are reported as mean ± SEM of triplicate experiments, ^*p<0.05, NS: not significant. ANOVA followed by Holm-Sidak post hoc tests. (B) Effect of collagen 1 on basal Ca²⁺ entry in the same batch of MCF-7 (a) and T-47D (b) cells using Mn²⁺ quenching experiments. Mean slope values are reported as mean ± SEM of triplicate experiments, ^*p<0.05, ANOVA followed by Holm-Sidak post hoc tests, NS: not significant.