COL1A1 and cancer: Moreover, we confirmed increased expression of collagen I (COL1A1, Col1) in PCa cells when exposed to conditioned media (CAF-CM) from lactate-rich CAFs compared to the lactate-poor fibroblasts (HPF-CM), obtained by healthy human prostatic tissues, as well as to LA, highlighting the role of environmental lactate, in sustaining cancer cell-derived Col1 synthesis (Fig. EV1B).