Calcium-permeable stretch-activated channel component. Probably involved in mechanosensing and in mechano-stimulated calcium uptake mechanism. Inhibited by GdCl(3), but not by verapamil. Expressed in roots, leaves, stems, flowers and siliques. In the root, high levels of expression in vascular tissues, in the stele and endodermis, but no expression in the cortex, epidermis, root cap, promeristem and adjacent elongation zone of the primary root. Not expressed in root hairs. Detected in shoot apical meristem, leaf mesophyll cells and vascular tissues, upper half of inflorescence, but not in petioles of rosette leaves. No visible phenotype when grown under normal conditions, due to redundancy with MCA1. The roots are able to normally sense the hardness of the growth medium. Mca1 and mca2 double mutant shows a strong growth defect.