EAST CAMBRIDGE, MASS. — A joint venture between LCOR, a development firm with three offices in the mid-Atlantic region, and San Francisco-based DivcoWest has begun leasing Park 151, a 468-unit apartment community located across the Charles River from Boston in East Cambridge. The 20-story building houses studio, one-, two- and three-bedroom units, 392 of which are market-rate apartments, 54 of which are affordable and 22 of which are penthouses. In addition, Park 151 features 19,000 square feet of ground-floor retail space. Amenities include a pool and lounge area, outdoor grilling stations, a fitness center, indoor and outdoor yoga spaces, a terrace and coworking and micro-office spaces. Rents start at roughly $2,900 per month for a studio apartment.